Virtualbox 'Auto-resize Guest Display' behaviour broke

ngoonee · 2022-09-21 22:33:09

I'm using KDE (X11) with Bismuth tiling. The symptoms described below are the same with or without Bismuth tiling enabled though.

When running my VirtualBox VM, I normally leave the 'Auto-resize Guest Display' box (under 'View' menu) checked. This used to work fine, but some time in the last.... 2 or 3 weeks the behaviour changed.

When 'working fine', the guest would resize resolution to match the size of the window (which would get tiled wherever), moving the window around would resize it sometimes, and the guest would then resize.

After the change, the guest would first resize resolution to match the window, then a couple of times a second it would resize to a slightly smaller resolution. So if I had the window tiled to the left, at first the guest would take up the whole left side of the monitor, but then it would shrink vertically bit by bit, within roughly 10 seconds it would only take up half the monitor.

The same symptoms happen without tiling, as long as I enable the option. The only way to avoid it is to full-screen the window, when that happens the guest just takes the full screen resolution and stays there.

Anyone else observed this and can corroborate that its not just something I've misconfigured? The guest is windows 11 but I suspect it won't make a difference what guest is running, seems to be something to do with how virtualbox is handling the hints sent to it.

seth · 2022-09-22 08:12:27

xprop

and click the vbox window.
Does it specify a resize increment != 1x1?

Did you try the behavior on a different WM (eg. openbox - so we know whether the client makes the wrong adjustments or the WM)?

ngoonee · 2022-09-22 13:24:46

seth wrote:

xprop
and click the vbox window.
Does it specify a resize increment != 1x1?

When 'Auto-resize Guest Display' is disabled, these are the WM_NORMAL_HINTS:-

WM_NORMAL_HINTS(WM_SIZE_HINTS):
                user specified location: 9, 74
                user specified size: 1265 by 1516
                program specified minimum size: 393 by 146
                program specified resize increment: 1 by 1
                program specified base size: 0 by 0
                window gravity: Static

But when it is enabled (and the behaviour is problematic):-

WM_NORMAL_HINTS(WM_SIZE_HINTS):
                user specified location: 9, 74
                user specified size: 1265 by 1516
                program specified minimum size: 393 by 145
                window gravity: Static

seth wrote:

Did you try the behavior on a different WM (eg. openbox - so we know whether the client makes the wrong adjustments or the WM)?

Not yet, will do so the next time I restart (am running something these few days).

seth · 2022-09-22 14:19:43

In the "enabled" case the window announces to be freely resizable, so it should™ no try to maintain a certain aspect.
In the "disabled" case it requires a 1x1 increment, but w/ the 0x0 base that creates an equal outcome (the window should be freely resizable, since the increment is a step, not a ratio - eg. my terminal has "6 by 14" what means you can grow in 6 horizontal or 14 vertical pixels, but of course the terminal will take random aspect ratios)

=> It's most likely VB that resizes itself based on some internal logic - usually a miscalculation about the window border (frame and titlebar)

xwininfo -all

and check xprop for _GTK_FRAME_EXTENTS (in case VB has some sort of CSD implementation)

Arch Linux

#1 2022-09-21 22:33:09

Virtualbox 'Auto-resize Guest Display' behaviour broke

#2 2022-09-22 08:12:27

Re: Virtualbox 'Auto-resize Guest Display' behaviour broke

#3 2022-09-22 13:24:46

Re: Virtualbox 'Auto-resize Guest Display' behaviour broke

#4 2022-09-22 14:19:43

Re: Virtualbox 'Auto-resize Guest Display' behaviour broke

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