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#1 2025-06-25 04:18:45

quyk
Member
Registered: 2020-04-22
Posts: 11

[Solved] KDE plasma window titlebars become large with 2nd display

I have a laptop with a newly installed KDE plasma 6.4.0 (wayland) desktop environment. When I use my second display (a Wacom Cintiq 22), all my window titlebars are rendered extremely large for some reason. Here are two screenshots that show how it looks normally and how it looks with the second display attached: https://imgur.com/a/V1lsRJz. Does anyone know what might be happening here? I can't find any settings that are relevant in the System Settings, and I'm not using any custom or 3rd-party themes. I tried a different monitor (an old Dell monitor) to see what would happen, but there were no issues. I have used the Cintiq monitor for several years with no issues under GNOME.

I don't know if this is related, but plasma always chooses 105% scaling on my displays by default (both the built-in laptop display and the Cintiq). Every time I redo the monitor configuration, I have to set it back to 100% so that the UI isn't blurry. However, when I attached the Dell monitor, it correctly chose 100% scaling.

Last edited by quyk (2025-06-26 08:30:04)

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#2 2025-06-25 06:46:01

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 73,723

Re: [Solved] KDE plasma window titlebars become large with 2nd display

This cannot be true, wayland handles HiDPI much more perfectly than X11 roll

iirc KDE follows the DPI of the primary output, but idk whether and how you can control that status on wayland (kscreen-doctor ?)

That all being said: the Wacom Cintiq 22 seems 1080p @ 22" - ie 100dpi, which isn't exactly "high".
What's your other monitor?

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#3 2025-06-26 05:40:09

quyk
Member
Registered: 2020-04-22
Posts: 11

Re: [Solved] KDE plasma window titlebars become large with 2nd display

seth wrote:

What's your other monitor?

My laptop model is "Lenovo YOGA C930-13IKB" and the built-in screen is identified as "AU Optronics eDP-1-0x303D", 1080p at 13.9". The old Dell monitor is "Dell Inc. DELL P2419H", 1080p at 23.8".

seth wrote:

iirc KDE follows the DPI of the primary output, but idk whether and how you can control that status on wayland (kscreen-doctor ?)

I did try changing the primary display as well as disabling the built-in screen, but neither change had any effect.

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#4 2025-06-26 06:33:47

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 73,723

Re: [Solved] KDE plasma window titlebars become large with 2nd display

Your eDP is ~160DPI, which counts as "high" - do you use both outputs at the same time or only the external one when the titlebars are too big? They're the right size on the eDP, no?
Leaving aside all the BS about "the wayland" magically fixing anything here, you could set the DPI to 120 for hybrid use.
KDE will likely adhere to https://wiki.archlinux.org/title/HiDPI#Qt_5 - interestingly this seems to only apply to the "breeze" decoration? Oxygen and Plastik look ok on your second screenshot?
Do you do anything else explicitly to manipulate HiDPI behavior?

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#5 2025-06-26 06:36:04

quyk
Member
Registered: 2020-04-22
Posts: 11

Re: [Solved] KDE plasma window titlebars become large with 2nd display

Okay, I've discovered some new information: I can reproduce the issue on the Dell monitor if I connect it using the same HDMI to USB-C docking station that I use for the Cintiq display. Previously, I was using an HDMI to USB-C cable and I didn't think the difference mattered because either way it was outputting to HDMI from USB-C.
Additionally, I learned that if I close all open windows and suspend the system, the problem disappears when I wake it back up. This tells me that the issue is certainly a bug, but I have no idea where in the software stack it is located...

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#6 2025-06-26 06:46:50

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 73,723

Re: [Solved] KDE plasma window titlebars become large with 2nd display

The dock might fudge the EDID?
For both attachment methods run

for OUT in /sys/class/drm/card*; do echo $OUT; edid-decode $OUT/edid; echo "================="; done

You'll need https://archlinux.org/packages/extra/x86_64/v4l-utils/

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#7 2025-06-26 07:03:53

quyk
Member
Registered: 2020-04-22
Posts: 11

Re: [Solved] KDE plasma window titlebars become large with 2nd display

Here is the output with the HDMI to USB-C cable:

/sys/class/drm/card1
/sys/class/drm/card1/edid: No such file or directory
=================
/sys/class/drm/card1-DP-1
edid-decode (hex):

00 ff ff ff ff ff ff 00 10 ac da d0 42 45 37 39
29 1d 01 03 80 35 1e 78 ea 05 65 a7 56 52 9c 27
0f 50 54 a5 4b 00 71 4f 81 80 a9 c0 d1 c0 01 01
01 01 01 01 01 01 02 3a 80 18 71 38 2d 40 58 2c
45 00 0f 28 21 00 00 1e 00 00 00 ff 00 42 4c 53
39 57 57 32 0a 20 20 20 20 20 00 00 00 fc 00 44
45 4c 4c 20 50 32 34 31 39 48 0a 20 00 00 00 fd
00 38 4c 1e 53 11 00 0a 20 20 20 20 20 20 01 df

02 03 17 b1 4c 90 05 04 03 02 07 16 01 14 1f 12
13 65 03 0c 00 10 00 02 3a 80 18 71 38 2d 40 58
2c 45 00 0f 28 21 00 00 1e 01 1d 80 18 71 1c 16
20 58 2c 25 00 0f 28 21 00 00 9e 01 1d 00 72 51
d0 1e 20 6e 28 55 00 0f 28 21 00 00 1e 8c 0a d0
8a 20 e0 2d 10 10 3e 96 00 0f 28 21 00 00 18 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 3d

----------------

Block 0, Base EDID:
  EDID Structure Version & Revision: 1.3
  Vendor & Product Identification:
    Manufacturer: DEL
    Model: 53466
    Serial Number: 959923522 (0x39374542)
    Made in: week 41 of 2019
  Basic Display Parameters & Features:
    Digital display
    Maximum image size: 53 cm x 30 cm
    Gamma: 2.20
    DPMS levels: Standby Suspend Off
    RGB color display
    First detailed timing is the preferred timing
  Color Characteristics:
    Red  : 0.6523, 0.3359
    Green: 0.3212, 0.6103
    Blue : 0.1533, 0.0605
    White: 0.3134, 0.3291
  Established Timings I & II:
    IBM     :   720x400    70.081663 Hz   9:5     31.467 kHz     28.320000 MHz
    DMT 0x04:   640x480    59.940476 Hz   4:3     31.469 kHz     25.175000 MHz
    DMT 0x06:   640x480    75.000000 Hz   4:3     37.500 kHz     31.500000 MHz
    DMT 0x09:   800x600    60.316541 Hz   4:3     37.879 kHz     40.000000 MHz
    DMT 0x0b:   800x600    75.000000 Hz   4:3     46.875 kHz     49.500000 MHz
    DMT 0x10:  1024x768    60.003840 Hz   4:3     48.363 kHz     65.000000 MHz
    DMT 0x12:  1024x768    75.028582 Hz   4:3     60.023 kHz     78.750000 MHz
    DMT 0x24:  1280x1024   75.024675 Hz   5:4     79.976 kHz    135.000000 MHz
  Standard Timings:
    DMT 0x15:  1152x864    75.000000 Hz   4:3     67.500 kHz    108.000000 MHz
    DMT 0x23:  1280x1024   60.019740 Hz   5:4     63.981 kHz    108.000000 MHz
    DMT 0x53:  1600x900    60.000000 Hz  16:9     60.000 kHz    108.000000 MHz (RB)
    DMT 0x52:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz
  Detailed Timing Descriptors:
    DTD 1:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (527 mm x 296 mm)
                 Hfront   88 Hsync  44 Hback  148 Hpol P
                 Vfront    4 Vsync   5 Vback   36 Vpol P
    Display Product Serial Number: 'BLS9WW2'
    Display Product Name: 'DELL P2419H'
    Display Range Limits:
      Monitor ranges (GTF): 56-76 Hz V, 30-83 kHz H, max dotclock 170 MHz
  Extension blocks: 1
Checksum: 0xdf

----------------

Block 1, CTA-861 Extension Block:
  Revision: 3
  Underscans IT Video Formats by default
  Supports YCbCr 4:4:4
  Supports YCbCr 4:2:2
  Native detailed modes: 1
  Video Data Block:
    VIC  16:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (native)
    VIC   5:  1920x1080i  60.000000 Hz  16:9     33.750 kHz     74.250000 MHz
    VIC   4:  1280x720    60.000000 Hz  16:9     45.000 kHz     74.250000 MHz
    VIC   3:   720x480    59.940060 Hz  16:9     31.469 kHz     27.000000 MHz
    VIC   2:   720x480    59.940060 Hz   4:3     31.469 kHz     27.000000 MHz
    VIC   7:  1440x480i   59.940060 Hz  16:9     15.734 kHz     27.000000 MHz
    VIC  22:  1440x576i   50.000000 Hz  16:9     15.625 kHz     27.000000 MHz
    VIC   1:   640x480    59.940476 Hz   4:3     31.469 kHz     25.175000 MHz
    VIC  20:  1920x1080i  50.000000 Hz  16:9     28.125 kHz     74.250000 MHz
    VIC  31:  1920x1080   50.000000 Hz  16:9     56.250 kHz    148.500000 MHz
    VIC  18:   720x576    50.000000 Hz  16:9     31.250 kHz     27.000000 MHz
    VIC  19:  1280x720    50.000000 Hz  16:9     37.500 kHz     74.250000 MHz
  Vendor-Specific Data Block (HDMI), OUI 00-0C-03:
    Source physical address: 1.0.0.0
  Detailed Timing Descriptors:
    DTD 2:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (527 mm x 296 mm)
                 Hfront   88 Hsync  44 Hback  148 Hpol P
                 Vfront    4 Vsync   5 Vback   36 Vpol P
    DTD 3:  1920x1080i  60.000000 Hz  16:9     33.750 kHz     74.250000 MHz (527 mm x 296 mm)
                 Hfront   88 Hsync  44 Hback  148 Hpol P
                 Vfront    2 Vsync   5 Vback   15 Vpol P Vfront +0.5 Odd Field
                 Vfront    2 Vsync   5 Vback   15 Vpol P Vback  +0.5 Even Field
    DTD 4:  1280x720    60.000000 Hz  16:9     45.000 kHz     74.250000 MHz (527 mm x 296 mm)
                 Hfront  110 Hsync  40 Hback  220 Hpol P
                 Vfront    5 Vsync   5 Vback   20 Vpol P
    DTD 5:   720x480    59.940060 Hz   3:2     31.469 kHz     27.000000 MHz (527 mm x 296 mm)
                 Hfront   16 Hsync  62 Hback   60 Hpol N
                 Vfront    9 Vsync   6 Vback   30 Vpol N
Checksum: 0x3d  Unused space in Extension Block: 32 bytes
=================
/sys/class/drm/card1-DP-2
EDID of '/sys/class/drm/card1-DP-2/edid' was empty.
=================
/sys/class/drm/card1-eDP-1
edid-decode (hex):

00 ff ff ff ff ff ff 00 06 af 3d 30 00 00 00 00
00 1a 01 04 a5 1f 11 78 02 fc 15 a0 55 50 9b 27
0c 50 54 00 00 00 01 01 01 01 01 01 01 01 01 01
01 01 01 01 01 01 14 37 80 b8 70 38 24 40 10 10
3e 00 35 ae 10 00 00 18 00 00 00 0f 00 00 00 00
00 00 00 00 00 00 00 00 00 20 00 00 00 fe 00 41
55 4f 0a 20 20 20 20 20 20 20 20 20 00 00 00 fe
00 42 31 33 39 48 41 4e 30 33 2e 30 20 0a 00 cb

----------------

Block 0, Base EDID:
  EDID Structure Version & Revision: 1.4
  Vendor & Product Identification:
    Manufacturer: AUO
    Model: 12349
    Made in: 2016
  Basic Display Parameters & Features:
    Digital display
    Bits per primary color channel: 8
    DisplayPort interface
    Maximum image size: 31 cm x 17 cm
    Gamma: 2.20
    Supported color formats: RGB 4:4:4
    First detailed timing includes the native pixel format and preferred refresh rate
  Color Characteristics:
    Red  : 0.6279, 0.3349
    Green: 0.3154, 0.6054
    Blue : 0.1523, 0.0478
    White: 0.3134, 0.3291
  Established Timings I & II: none
  Standard Timings: none
  Detailed Timing Descriptors:
    DTD 1:  1920x1080   60.049471 Hz  16:9     67.015 kHz    141.000000 MHz (309 mm x 174 mm)
                 Hfront   16 Hsync  16 Hback  152 Hpol N
                 Vfront    3 Vsync  14 Vback   19 Vpol N
    Manufacturer-Specified Display Descriptor (0x0f): 00 0f 00 00 00 00 00 00 00 00 00 00 00 00 00 20 '............... '
    Alphanumeric Data String: 'AUO'
    Alphanumeric Data String: 'B139HAN03.0 '
Checksum: 0xcb
=================

Here is the output with the HDMI to USB-C dock:

/sys/class/drm/card1
/sys/class/drm/card1/edid: No such file or directory
=================
/sys/class/drm/card1-DP-1
edid-decode (hex):

00 ff ff ff ff ff ff 00 10 ac da d0 42 45 37 39
29 1d 01 03 80 35 1e 78 ea 05 65 a7 56 52 9c 27
0f 50 54 a5 4b 00 71 4f 81 80 a9 c0 d1 c0 01 01
01 01 01 01 01 01 02 3a 80 18 71 38 2d 40 58 2c
45 00 0f 28 21 00 00 1e 00 00 00 ff 00 42 4c 53
39 57 57 32 0a 20 20 20 20 20 00 00 00 fc 00 44
45 4c 4c 20 50 32 34 31 39 48 0a 20 00 00 00 fd
00 38 4c 1e 53 11 00 0a 20 20 20 20 20 20 01 df

02 03 17 b1 4c 90 05 04 03 02 07 16 01 14 1f 12
13 65 03 0c 00 10 00 02 3a 80 18 71 38 2d 40 58
2c 45 00 0f 28 21 00 00 1e 01 1d 80 18 71 1c 16
20 58 2c 25 00 0f 28 21 00 00 9e 01 1d 00 72 51
d0 1e 20 6e 28 55 00 0f 28 21 00 00 1e 8c 0a d0
8a 20 e0 2d 10 10 3e 96 00 0f 28 21 00 00 18 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 3d

----------------

Block 0, Base EDID:
  EDID Structure Version & Revision: 1.3
  Vendor & Product Identification:
    Manufacturer: DEL
    Model: 53466
    Serial Number: 959923522 (0x39374542)
    Made in: week 41 of 2019
  Basic Display Parameters & Features:
    Digital display
    Maximum image size: 53 cm x 30 cm
    Gamma: 2.20
    DPMS levels: Standby Suspend Off
    RGB color display
    First detailed timing is the preferred timing
  Color Characteristics:
    Red  : 0.6523, 0.3359
    Green: 0.3212, 0.6103
    Blue : 0.1533, 0.0605
    White: 0.3134, 0.3291
  Established Timings I & II:
    IBM     :   720x400    70.081663 Hz   9:5     31.467 kHz     28.320000 MHz
    DMT 0x04:   640x480    59.940476 Hz   4:3     31.469 kHz     25.175000 MHz
    DMT 0x06:   640x480    75.000000 Hz   4:3     37.500 kHz     31.500000 MHz
    DMT 0x09:   800x600    60.316541 Hz   4:3     37.879 kHz     40.000000 MHz
    DMT 0x0b:   800x600    75.000000 Hz   4:3     46.875 kHz     49.500000 MHz
    DMT 0x10:  1024x768    60.003840 Hz   4:3     48.363 kHz     65.000000 MHz
    DMT 0x12:  1024x768    75.028582 Hz   4:3     60.023 kHz     78.750000 MHz
    DMT 0x24:  1280x1024   75.024675 Hz   5:4     79.976 kHz    135.000000 MHz
  Standard Timings:
    DMT 0x15:  1152x864    75.000000 Hz   4:3     67.500 kHz    108.000000 MHz
    DMT 0x23:  1280x1024   60.019740 Hz   5:4     63.981 kHz    108.000000 MHz
    DMT 0x53:  1600x900    60.000000 Hz  16:9     60.000 kHz    108.000000 MHz (RB)
    DMT 0x52:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz
  Detailed Timing Descriptors:
    DTD 1:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (527 mm x 296 mm)
                 Hfront   88 Hsync  44 Hback  148 Hpol P
                 Vfront    4 Vsync   5 Vback   36 Vpol P
    Display Product Serial Number: 'BLS9WW2'
    Display Product Name: 'DELL P2419H'
    Display Range Limits:
      Monitor ranges (GTF): 56-76 Hz V, 30-83 kHz H, max dotclock 170 MHz
  Extension blocks: 1
Checksum: 0xdf

----------------

Block 1, CTA-861 Extension Block:
  Revision: 3
  Underscans IT Video Formats by default
  Supports YCbCr 4:4:4
  Supports YCbCr 4:2:2
  Native detailed modes: 1
  Video Data Block:
    VIC  16:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (native)
    VIC   5:  1920x1080i  60.000000 Hz  16:9     33.750 kHz     74.250000 MHz
    VIC   4:  1280x720    60.000000 Hz  16:9     45.000 kHz     74.250000 MHz
    VIC   3:   720x480    59.940060 Hz  16:9     31.469 kHz     27.000000 MHz
    VIC   2:   720x480    59.940060 Hz   4:3     31.469 kHz     27.000000 MHz
    VIC   7:  1440x480i   59.940060 Hz  16:9     15.734 kHz     27.000000 MHz
    VIC  22:  1440x576i   50.000000 Hz  16:9     15.625 kHz     27.000000 MHz
    VIC   1:   640x480    59.940476 Hz   4:3     31.469 kHz     25.175000 MHz
    VIC  20:  1920x1080i  50.000000 Hz  16:9     28.125 kHz     74.250000 MHz
    VIC  31:  1920x1080   50.000000 Hz  16:9     56.250 kHz    148.500000 MHz
    VIC  18:   720x576    50.000000 Hz  16:9     31.250 kHz     27.000000 MHz
    VIC  19:  1280x720    50.000000 Hz  16:9     37.500 kHz     74.250000 MHz
  Vendor-Specific Data Block (HDMI), OUI 00-0C-03:
    Source physical address: 1.0.0.0
  Detailed Timing Descriptors:
    DTD 2:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (527 mm x 296 mm)
                 Hfront   88 Hsync  44 Hback  148 Hpol P
                 Vfront    4 Vsync   5 Vback   36 Vpol P
    DTD 3:  1920x1080i  60.000000 Hz  16:9     33.750 kHz     74.250000 MHz (527 mm x 296 mm)
                 Hfront   88 Hsync  44 Hback  148 Hpol P
                 Vfront    2 Vsync   5 Vback   15 Vpol P Vfront +0.5 Odd Field
                 Vfront    2 Vsync   5 Vback   15 Vpol P Vback  +0.5 Even Field
    DTD 4:  1280x720    60.000000 Hz  16:9     45.000 kHz     74.250000 MHz (527 mm x 296 mm)
                 Hfront  110 Hsync  40 Hback  220 Hpol P
                 Vfront    5 Vsync   5 Vback   20 Vpol P
    DTD 5:   720x480    59.940060 Hz   3:2     31.469 kHz     27.000000 MHz (527 mm x 296 mm)
                 Hfront   16 Hsync  62 Hback   60 Hpol N
                 Vfront    9 Vsync   6 Vback   30 Vpol N
Checksum: 0x3d  Unused space in Extension Block: 32 bytes
=================
/sys/class/drm/card1-DP-2
EDID of '/sys/class/drm/card1-DP-2/edid' was empty.
=================
/sys/class/drm/card1-eDP-1
edid-decode (hex):

00 ff ff ff ff ff ff 00 06 af 3d 30 00 00 00 00
00 1a 01 04 a5 1f 11 78 02 fc 15 a0 55 50 9b 27
0c 50 54 00 00 00 01 01 01 01 01 01 01 01 01 01
01 01 01 01 01 01 14 37 80 b8 70 38 24 40 10 10
3e 00 35 ae 10 00 00 18 00 00 00 0f 00 00 00 00
00 00 00 00 00 00 00 00 00 20 00 00 00 fe 00 41
55 4f 0a 20 20 20 20 20 20 20 20 20 00 00 00 fe
00 42 31 33 39 48 41 4e 30 33 2e 30 20 0a 00 cb

----------------

Block 0, Base EDID:
  EDID Structure Version & Revision: 1.4
  Vendor & Product Identification:
    Manufacturer: AUO
    Model: 12349
    Made in: 2016
  Basic Display Parameters & Features:
    Digital display
    Bits per primary color channel: 8
    DisplayPort interface
    Maximum image size: 31 cm x 17 cm
    Gamma: 2.20
    Supported color formats: RGB 4:4:4
    First detailed timing includes the native pixel format and preferred refresh rate
  Color Characteristics:
    Red  : 0.6279, 0.3349
    Green: 0.3154, 0.6054
    Blue : 0.1523, 0.0478
    White: 0.3134, 0.3291
  Established Timings I & II: none
  Standard Timings: none
  Detailed Timing Descriptors:
    DTD 1:  1920x1080   60.049471 Hz  16:9     67.015 kHz    141.000000 MHz (309 mm x 174 mm)
                 Hfront   16 Hsync  16 Hback  152 Hpol N
                 Vfront    3 Vsync  14 Vback   19 Vpol N
    Manufacturer-Specified Display Descriptor (0x0f): 00 0f 00 00 00 00 00 00 00 00 00 00 00 00 00 20 '............... '
    Alphanumeric Data String: 'AUO'
    Alphanumeric Data String: 'B139HAN03.0 '
Checksum: 0xcb
=================

I collected these with the Dell monitor because I don't have enough ports to properly attach the Cintiq without the dock.

Last edited by quyk (2025-06-26 07:05:37)

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#8 2025-06-26 07:30:45

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 73,723

Re: [Solved] KDE plasma window titlebars become large with 2nd display

Identical, same resolutions, same physical size - this doesn't explain the difference at all.
Does kscreen-doctor report anything different?

Do you do anything else explicitly to manipulate HiDPI behavior?

printenv

Might also be a stale bogus config?
https://wiki.archlinux.org/title/KDE#Un … lution_set (though not event the output names change depending on the attachment method if the provided outputs are correct…)

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#9 2025-06-26 08:02:41

quyk
Member
Registered: 2020-04-22
Posts: 11

Re: [Solved] KDE plasma window titlebars become large with 2nd display

Do you do anything else explicitly to manipulate HiDPI behavior?

No, I don't think so. The only display setting I changed was Display & Monitor > Display Configuration > Scale. It was set to 105% by default, and I changed it to 100%.

seth wrote:

Identical, same resolutions, same physical size - this doesn't explain the difference at all.
Does kscreen-doctor report anything different?

The output of "kscreen-doctor --outputs" is identical either way:

Output: 1 eDP-1 f569541b-2ba8-47c8-967e-c197fca1e66b
        enabled
        connected
        priority 1
        Panel
        replication source:0
        Modes:  1:1920x1080@60*!  2:1280x1024@60  3:1280x1024@60  4:1024x768@60  5:1024x768@60  6:1280x800@60  7:1280x800@60  8:1600x900@60  9:1600x900@60  10:1368x768@60  11:1368x768@60  12:1280x720@60  13:1280x720@60
        Geometry: 1920,0 1920x1080
        Scale: 1
        Rotation: 1
        Overscan: 0
        Vrr: incapable
        RgbRange: Automatic
        HDR: incapable
        Wide Color Gamut: incapable
        ICC profile: none
        Color profile source: sRGB
        Color power preference: prefer efficiency and performance
        Brightness control: supported, set to 95% and dimming to 100%
        Color resolution: automatic (10), range: [6; 12] bits per color
        Allow EDR: always
Output: 2 DP-1 1f0677a0-0e64-43a5-a887-31987d969e9e
        enabled
        connected
        priority 2
        DisplayPort
        replication source:0
        Modes:  14:1920x1080@60*!  15:1920x1080@60  16:1920x1080@60  17:1920x1080@60  18:1920x1080@60  19:1920x1080@60  20:1920x1080@50  21:1920x1080@50  22:1600x900@60  23:1280x1024@75  24:1280x1024@60  25:1152x864@75  26:1280x720@60  27:1280x720@60  28:1280x720@60  29:1280x720@50  30:1024x768@75  31:1024x768@60  32:800x600@75  33:800x600@60  34:720x576@50  35:720x480@60  36:720x480@60  37:720x480@60  38:720x480@60  39:720x480@60  40:640x480@75  41:640x480@60  42:640x480@60  43:640x480@60  44:720x400@70
        Geometry: 0,0 1920x1080
        Scale: 1
        Rotation: 1
        Overscan: 0
        Vrr: incapable
        RgbRange: Automatic
        HDR: incapable
        Wide Color Gamut: incapable
        ICC profile: none
        Color profile source: sRGB
        Color power preference: prefer efficiency and performance
        Brightness control: unsupported
        DDC/CI: allowed
        Color resolution: automatic (10), range: [6; 12] bits per color
        Allow EDR: unsupported

The output of "kscreen-doctor --json" shows only one difference: "tabletModeEngaged" is true when the dock is attached, but false otherwise. Here's the output when using the dock:

{
    "features": 255,
    "outputs": [
        {
            "autoRotatePolicy": 1,
            "brightness": 0.95,
            "clones": [
            ],
            "connected": true,
            "currentModeId": "1",
            "edrPolicy": 1,
            "enabled": true,
            "followPreferredMode": false,
            "iccProfilePath": "",
            "icon": "",
            "id": 1,
            "maxBpc": 0,
            "modes": [
                {
                    "id": "1",
                    "name": "1920x1080@60",
                    "refreshRate": 60.04899978637695,
                    "size": {
                        "height": 1080,
                        "width": 1920
                    }
                },
                {
                    "id": "10",
                    "name": "1368x768@60",
                    "refreshRate": 59.88199996948242,
                    "size": {
                        "height": 768,
                        "width": 1368
                    }
                },
                {
                    "id": "11",
                    "name": "1368x768@60",
                    "refreshRate": 59.88199996948242,
                    "size": {
                        "height": 768,
                        "width": 1368
                    }
                },
                {
                    "id": "12",
                    "name": "1280x720@60",
                    "refreshRate": 59.85499954223633,
                    "size": {
                        "height": 720,
                        "width": 1280
                    }
                },
                {
                    "id": "13",
                    "name": "1280x720@60",
                    "refreshRate": 59.85499954223633,
                    "size": {
                        "height": 720,
                        "width": 1280
                    }
                },
                {
                    "id": "2",
                    "name": "1280x1024@60",
                    "refreshRate": 59.89500045776367,
                    "size": {
                        "height": 1024,
                        "width": 1280
                    }
                },
                {
                    "id": "3",
                    "name": "1280x1024@60",
                    "refreshRate": 59.89500045776367,
                    "size": {
                        "height": 1024,
                        "width": 1280
                    }
                },
                {
                    "id": "4",
                    "name": "1024x768@60",
                    "refreshRate": 59.91999816894531,
                    "size": {
                        "height": 768,
                        "width": 1024
                    }
                },
                {
                    "id": "5",
                    "name": "1024x768@60",
                    "refreshRate": 59.91999816894531,
                    "size": {
                        "height": 768,
                        "width": 1024
                    }
                },
                {
                    "id": "6",
                    "name": "1280x800@60",
                    "refreshRate": 59.810001373291016,
                    "size": {
                        "height": 800,
                        "width": 1280
                    }
                },
                {
                    "id": "7",
                    "name": "1280x800@60",
                    "refreshRate": 59.98899841308594,
                    "size": {
                        "height": 800,
                        "width": 1280
                    }
                },
                {
                    "id": "8",
                    "name": "1600x900@60",
                    "refreshRate": 59.94599914550781,
                    "size": {
                        "height": 900,
                        "width": 1600
                    }
                },
                {
                    "id": "9",
                    "name": "1600x900@60",
                    "refreshRate": 59.94599914550781,
                    "size": {
                        "height": 900,
                        "width": 1600
                    }
                }
            ],
            "name": "eDP-1",
            "pos": {
                "x": 1920,
                "y": 0
            },
            "preferredModes": [
                "1"
            ],
            "priority": 1,
            "replicationSource": 0,
            "rgbRange": 0,
            "rotation": 1,
            "scale": 1,
            "size": {
                "height": 1080,
                "width": 1920
            },
            "sizeMM": {
                "height": 174,
                "width": 309
            },
            "type": 7
        },
        {
            "clones": [
            ],
            "connected": true,
            "currentModeId": "14",
            "ddcCiAllowed": true,
            "enabled": true,
            "followPreferredMode": false,
            "iccProfilePath": "",
            "icon": "",
            "id": 2,
            "maxBpc": 0,
            "modes": [
                {
                    "id": "14",
                    "name": "1920x1080@60",
                    "refreshRate": 60,
                    "size": {
                        "height": 1080,
                        "width": 1920
                    }
                },
                {
                    "id": "15",
                    "name": "1920x1080@60",
                    "refreshRate": 60,
                    "size": {
                        "height": 1080,
                        "width": 1920
                    }
                },
                {
                    "id": "16",
                    "name": "1920x1080@60",
                    "refreshRate": 59.939998626708984,
                    "size": {
                        "height": 1080,
                        "width": 1920
                    }
                },
                {
                    "id": "17",
                    "name": "1920x1080@60",
                    "refreshRate": 60,
                    "size": {
                        "height": 1080,
                        "width": 1920
                    }
                },
                {
                    "id": "18",
                    "name": "1920x1080@60",
                    "refreshRate": 60,
                    "size": {
                        "height": 1080,
                        "width": 1920
                    }
                },
                {
                    "id": "19",
                    "name": "1920x1080@60",
                    "refreshRate": 59.939998626708984,
                    "size": {
                        "height": 1080,
                        "width": 1920
                    }
                },
                {
                    "id": "20",
                    "name": "1920x1080@50",
                    "refreshRate": 50,
                    "size": {
                        "height": 1080,
                        "width": 1920
                    }
                },
                {
                    "id": "21",
                    "name": "1920x1080@50",
                    "refreshRate": 50,
                    "size": {
                        "height": 1080,
                        "width": 1920
                    }
                },
                {
                    "id": "22",
                    "name": "1600x900@60",
                    "refreshRate": 60,
                    "size": {
                        "height": 900,
                        "width": 1600
                    }
                },
                {
                    "id": "23",
                    "name": "1280x1024@75",
                    "refreshRate": 75.0250015258789,
                    "size": {
                        "height": 1024,
                        "width": 1280
                    }
                },
                {
                    "id": "24",
                    "name": "1280x1024@60",
                    "refreshRate": 60.02000045776367,
                    "size": {
                        "height": 1024,
                        "width": 1280
                    }
                },
                {
                    "id": "25",
                    "name": "1152x864@75",
                    "refreshRate": 75,
                    "size": {
                        "height": 864,
                        "width": 1152
                    }
                },
                {
                    "id": "26",
                    "name": "1280x720@60",
                    "refreshRate": 60,
                    "size": {
                        "height": 720,
                        "width": 1280
                    }
                },
                {
                    "id": "27",
                    "name": "1280x720@60",
                    "refreshRate": 60,
                    "size": {
                        "height": 720,
                        "width": 1280
                    }
                },
                {
                    "id": "28",
                    "name": "1280x720@60",
                    "refreshRate": 59.939998626708984,
                    "size": {
                        "height": 720,
                        "width": 1280
                    }
                },
                {
                    "id": "29",
                    "name": "1280x720@50",
                    "refreshRate": 50,
                    "size": {
                        "height": 720,
                        "width": 1280
                    }
                },
                {
                    "id": "30",
                    "name": "1024x768@75",
                    "refreshRate": 75.02899932861328,
                    "size": {
                        "height": 768,
                        "width": 1024
                    }
                },
                {
                    "id": "31",
                    "name": "1024x768@60",
                    "refreshRate": 60.00400161743164,
                    "size": {
                        "height": 768,
                        "width": 1024
                    }
                },
                {
                    "id": "32",
                    "name": "800x600@75",
                    "refreshRate": 75,
                    "size": {
                        "height": 600,
                        "width": 800
                    }
                },
                {
                    "id": "33",
                    "name": "800x600@60",
                    "refreshRate": 60.31700134277344,
                    "size": {
                        "height": 600,
                        "width": 800
                    }
                },
                {
                    "id": "34",
                    "name": "720x576@50",
                    "refreshRate": 50,
                    "size": {
                        "height": 576,
                        "width": 720
                    }
                },
                {
                    "id": "35",
                    "name": "720x480@60",
                    "refreshRate": 60,
                    "size": {
                        "height": 480,
                        "width": 720
                    }
                },
                {
                    "id": "36",
                    "name": "720x480@60",
                    "refreshRate": 60,
                    "size": {
                        "height": 480,
                        "width": 720
                    }
                },
                {
                    "id": "37",
                    "name": "720x480@60",
                    "refreshRate": 59.939998626708984,
                    "size": {
                        "height": 480,
                        "width": 720
                    }
                },
                {
                    "id": "38",
                    "name": "720x480@60",
                    "refreshRate": 59.939998626708984,
                    "size": {
                        "height": 480,
                        "width": 720
                    }
                },
                {
                    "id": "39",
                    "name": "720x480@60",
                    "refreshRate": 59.939998626708984,
                    "size": {
                        "height": 480,
                        "width": 720
                    }
                },
                {
                    "id": "40",
                    "name": "640x480@75",
                    "refreshRate": 75,
                    "size": {
                        "height": 480,
                        "width": 640
                    }
                },
                {
                    "id": "41",
                    "name": "640x480@60",
                    "refreshRate": 60,
                    "size": {
                        "height": 480,
                        "width": 640
                    }
                },
                {
                    "id": "42",
                    "name": "640x480@60",
                    "refreshRate": 59.939998626708984,
                    "size": {
                        "height": 480,
                        "width": 640
                    }
                },
                {
                    "id": "43",
                    "name": "640x480@60",
                    "refreshRate": 59.939998626708984,
                    "size": {
                        "height": 480,
                        "width": 640
                    }
                },
                {
                    "id": "44",
                    "name": "720x400@70",
                    "refreshRate": 70.08200073242188,
                    "size": {
                        "height": 400,
                        "width": 720
                    }
                }
            ],
            "name": "DP-1",
            "pos": {
                "x": 0,
                "y": 0
            },
            "preferredModes": [
                "14"
            ],
            "priority": 2,
            "replicationSource": 0,
            "rgbRange": 0,
            "rotation": 1,
            "scale": 1,
            "size": {
                "height": 1080,
                "width": 1920
            },
            "sizeMM": {
                "height": 296,
                "width": 527
            },
            "type": 14
        }
    ],
    "screen": {
        "currentSize": {
            "height": 1080,
            "width": 3840
        },
        "id": 0,
        "maxActiveOutputsCount": 2,
        "maxSize": {
            "height": 64000,
            "width": 64000
        },
        "minSize": {
            "height": 0,
            "width": 0
        }
    },
    "tabletModeAvailable": true,
    "tabletModeEngaged": true
}
seth wrote:
printenv

Here's with the cable:

COLORFGBG=15;0
COLORTERM=truecolor
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
DEBUGINFOD_URLS=https://debuginfod.archlinux.org 
DESKTOP_SESSION=plasma
DISPLAY=:1
GTK2_RC_FILES=/etc/gtk-2.0/gtkrc:/home/quytelda/.gtkrc-2.0:/home/quytelda/.config/gtkrc-2.0
GTK_RC_FILES=/etc/gtk/gtkrc:/home/quytelda/.gtkrc:/home/quytelda/.config/gtkrc
HOME=/home/quytelda
ICEAUTHORITY=/run/user/1000/iceauth_HSEhmU
INVOCATION_ID=0f9b498ab6684ce69964f42034963753
JOURNAL_STREAM=9:9166
KDE_APPLICATIONS_AS_SCOPE=1
KDE_FULL_SESSION=true
KDE_SESSION_UID=1000
KDE_SESSION_VERSION=6
KONSOLE_DBUS_SERVICE=:1.53
KONSOLE_DBUS_SESSION=/Sessions/1
KONSOLE_DBUS_WINDOW=/Windows/1
KONSOLE_VERSION=250402
LANG=en_US.UTF-8
LANGUAGE=
LOGNAME=quytelda
MAIL=/var/spool/mail/quytelda
MANAGERPID=673
MEMORY_PRESSURE_WATCH=/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/session.slice/plasma-plasmashell.service/memory.pressure
MEMORY_PRESSURE_WRITE=c29tZSAyMDAwMDAgMjAwMDAwMAA=
MOTD_SHOWN=pam
OLDPWD=/home/quytelda
PAM_KWALLET5_LOGIN=/run/user/1000/kwallet5.socket
PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/home/quytelda/.local/bin
PROFILEHOME=
PWD=/home/quytelda
QT_WAYLAND_RECONNECT=1
SESSION_MANAGER=local/kanjal:@/tmp/.ICE-unix/878,unix/kanjal:/tmp/.ICE-unix/878
SHELL=/usr/bin/zsh
SHELL_SESSION_ID=a1f25f8110254271bfb709d7d514496f
SHLVL=1
SYSTEMD_EXEC_PID=917
TERM=tmux-256color
TERM_PROGRAM=tmux
TERM_PROGRAM_VERSION=3.5a
TMUX=/tmp/tmux-1000/default,1736,2
TMUX_PANE=%2
USER=quytelda
WAYLAND_DISPLAY=wayland-0
WINDOWID=94109367515248
XAUTHORITY=/run/user/1000/xauth_GfvCMq
XDG_CONFIG_DIRS=/home/quytelda/.config/kdedefaults:/etc/xdg
XDG_CURRENT_DESKTOP=KDE
XDG_DATA_DIRS=/home/quytelda/.local/share/flatpak/exports/share:/var/lib/flatpak/exports/share:/usr/local/share:/usr/share
XDG_MENU_PREFIX=plasma-
XDG_RUNTIME_DIR=/run/user/1000
XDG_SEAT=seat0
XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0
XDG_SESSION_CLASS=user
XDG_SESSION_DESKTOP=KDE
XDG_SESSION_ID=2
XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session1
XDG_SESSION_TYPE=wayland
XDG_VTNR=1
_=/usr/bin/printenv
DOCKER_CONTENT_TRUST=1
EDITOR=emacs -nw
GPG_TTY=/dev/pts/4
LIBVIRT_DEFAULT_URI=qemu:///system
LC_MESSAGES=

With the dock:

COLORFGBG=15;0
COLORTERM=truecolor
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
DEBUGINFOD_URLS=https://debuginfod.archlinux.org 
DESKTOP_SESSION=plasma
DISPLAY=:1
GTK2_RC_FILES=/etc/gtk-2.0/gtkrc:/home/quytelda/.gtkrc-2.0:/home/quytelda/.config/gtkrc-2.0
GTK_RC_FILES=/etc/gtk/gtkrc:/home/quytelda/.gtkrc:/home/quytelda/.config/gtkrc
HOME=/home/quytelda
ICEAUTHORITY=/run/user/1000/iceauth_PlhttA
INVOCATION_ID=55845f1231eb41818c881b9a7f0830cb
JOURNAL_STREAM=9:7070
KDE_APPLICATIONS_AS_SCOPE=1
KDE_FULL_SESSION=true
KDE_SESSION_UID=1000
KDE_SESSION_VERSION=6
KONSOLE_DBUS_SERVICE=:1.49
KONSOLE_DBUS_SESSION=/Sessions/1
KONSOLE_DBUS_WINDOW=/Windows/1
KONSOLE_VERSION=250402
LANG=en_US.UTF-8
LANGUAGE=
LOGNAME=quytelda
MAIL=/var/spool/mail/quytelda
MANAGERPID=696
MEMORY_PRESSURE_WATCH=/sys/fs/cgroup/user.slice/user-1000.slice/user@1000.service/session.slice/plasma-plasmashell.service/memory.pressure
MEMORY_PRESSURE_WRITE=c29tZSAyMDAwMDAgMjAwMDAwMAA=
MOTD_SHOWN=pam
OLDPWD=/home/quytelda
PAM_KWALLET5_LOGIN=/run/user/1000/kwallet5.socket
PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/home/quytelda/.local/bin
PROFILEHOME=
PWD=/home/quytelda
QT_WAYLAND_RECONNECT=1
SESSION_MANAGER=local/kanjal:@/tmp/.ICE-unix/906,unix/kanjal:/tmp/.ICE-unix/906
SHELL=/usr/bin/zsh
SHELL_SESSION_ID=2aff8a7e026a473aaaead06d86b33bcd
SHLVL=1
SYSTEMD_EXEC_PID=936
TERM=tmux-256color
TERM_PROGRAM=tmux
TERM_PROGRAM_VERSION=3.5a
TMUX=/tmp/tmux-1000/default,1290,0
TMUX_PANE=%0
USER=quytelda
WAYLAND_DISPLAY=wayland-0
WINDOWID=94530019812128
XAUTHORITY=/run/user/1000/xauth_TaoQbj
XDG_CONFIG_DIRS=/home/quytelda/.config/kdedefaults:/etc/xdg
XDG_CURRENT_DESKTOP=KDE
XDG_DATA_DIRS=/home/quytelda/.local/share/flatpak/exports/share:/var/lib/flatpak/exports/share:/usr/local/share:/usr/share
XDG_MENU_PREFIX=plasma-
XDG_RUNTIME_DIR=/run/user/1000
XDG_SEAT=seat0
XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0
XDG_SESSION_CLASS=user
XDG_SESSION_DESKTOP=KDE
XDG_SESSION_ID=2
XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session1
XDG_SESSION_TYPE=wayland
XDG_VTNR=1
_=/usr/bin/printenv
DOCKER_CONTENT_TRUST=1
EDITOR=emacs -nw
GPG_TTY=/dev/pts/2
LIBVIRT_DEFAULT_URI=qemu:///system
LC_MESSAGES=
seth wrote:

Might also be a stale bogus config?
https://wiki.archlinux.org/title/KDE#Un … lution_set (though not event the output names change depending on the attachment method if the provided outputs are correct\u2026)

~/.local/share/kscreen doesn't exist for me. For what it's worth, I did try deleting all my dotfiles and rebuilding from scratch yesterday, but the issue remained.

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#10 2025-06-26 08:26:31

quyk
Member
Registered: 2020-04-22
Posts: 11

Re: [Solved] KDE plasma window titlebars become large with 2nd display

Well, it looks like the "tabletModeEngaged" setting was the problem. Here's my understanding of what is happening:

Plasma has a "Touch Mode" that enlarges UI elements for easier touch usage. This mode is supposed to engage when the system detects a touchscreen but no keyboard/mouse. When I use my dock, the laptop firmware disables the built-in keyboard and mouse. However, I am still using a USB keyboard and mouse. For whatever reason, plasma doesn't realize that I still have a keyboard and mouse attached, and enables touch mode when the dock is used. I can disable touch mode in "General Behavior > Touch".

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#11 2025-06-26 08:30:49

seth
Member
From: Don't DM me only for attention
Registered: 2012-09-03
Posts: 73,723

Re: [Solved] KDE plasma window titlebars become large with 2nd display

only one difference: "tabletModeEngaged" is true when the dock is attached, but false otherwise

I'm gonna say you've a winner here - kde likely enters some touchpad mode, hence the oversized buttons.
And apparently the conditions are misjudged and the behavior is spurious.

Gemini says "To disable tablet mode in KDE Plasma, navigate to System Settings > Workspace Behavior > Touch Mode and select Never Enabled." and I guess it's reasonable enough to at least look there wink
Then file a bug at bugs.kde.org

Edit: F5…

Last edited by seth (2025-06-26 08:31:06)

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