kdiff3 on xfce 4.14.5, window decorations missing?

[Olivier Fourdan]

Hi,

On Mon, 12 Oct 2020 at 23:49, Mark Mielke <mark.mielke at gmail.com> wrote:
>
> This was first encountered on Oracle Linux 8.2 + EPEL with xfwm4
> 4.14.2 + kdiff3 1.8.4 + TigerVNC 1.10.1.
>
> Sometimes the kdiff3 window decorations would be missing. I was able
> to reproduce this on Fedora 32. 50% of the time I can reproduce with:
>
> 1) Inside a TigerVNC + XFCE session
> 2) Launch "kdiff3" with no arguments from a terminal window.
> 3) If the window + open file dialog comes up ok, first close the open
> file dialog, then maximize the kdiff3 window and try again to launch
> "kdiff3" with no arguments from a terminal window.
> 4) The main window (QMainWindow, since this is a KDE / Qt app?) is
> missing decorations. The dialog window looks fine.
>
> I found a few fixes in 4.14.x related to windows decorations,
> including a gsetting / glib corruption issue. But, the same problem
> happens with xfwm4 4.14.5 on both Oracle Linux 8.2 and Fedora 32.
>
> Any ideas of where to start looking here? I don't mind trying patches
> or even writing patches - but I need help knowing where to start. All
> the known issues seem to be addressed in 4.14.5, and don't seem to
> have fixed the problem.

I think it's a bug in kdiff3, not xfwm4.

For some reason kdiff3 switches to fullscreen in that situation, hence
the non-decorated window. FWIW, it's the same in GNOME afaics.

I think it's a race, kdiff3 trying to restore a wrong state at startup
or something.

You should be able to restore the original size of the window (and its
decoration) pressing [Alt]+[F11].

HTH
Cheers
Olivier