alt+tab shows wrong icon

[enzonun]

Expected behaviour

Show correct gimp icon, ( also happens with other apps, it shows wrong icon or pixelated icons)
( Something similar to this )

Actual behaviour

Steps to reproduce the behaviour

open gimp, press Alt+tab and see the icon

MATE general version

1.26.0

Package version

Linux Distribution

Fedora 36

Link to bugreport of your Distribution (requirement)

[cwendling]

I think what you see is that Marco (MATE's window manager) is showing you the window icon, whereas gnome-shell is showing the app icon (e.g. as defined in the .desktop).

In most cases it'll be the same, because the usual thing apps do is simply set their windows icon to their app's one. Gimp is doing something different: it is compositing the current open image with a grey logo (try and open a photo, and display the switcher again).

What is the right thing to do? I guess it's a matter of opinion, but I would say MATE isn't doing anything wrong here. But it possibly could do something different indeed… whether it should or not? dunno 🤷

[raveit65]

I am still wondering about the preview button.
marco alt-tab looks like this under fedora 36

And why should this icon be wrong?
Edit: screenshot is with compositor on

[lukefromdc]

Is this with compositing on or off?

[enzonun]

Is this with compositing on or off?
on AND off

[lukefromdc]

OK, I was not able to duplicate this with GIMP and compositing on in Marco. Gimp adds an icon for the image you are working on to the basic GIMP icon for its window icon. When I turned off thumbnailing windows for this test, the full GIMP combined icon came up just fine. This could be an issue with GIMP itself (we may have different versions) if you don't see this with any other package. Also note that I am using a hacked version of libwnck to support hidpi and properly render icons with window-scaling !=1 if that makes any difference. Using a 4K monitor, window-scaling=2, and AMDGPU graphics. The GPU driver should have no effect on this in theory, but I once had panel issues on an old netbook after a Mesa Intel GPU driver update on it. That was probably the interaction between the driver and some Xorg feature.