KDE Plasma 5.8 LTS doesn't render transparency effects

What distribution is this?

There was a change in Onboard in version 1.2 that dropped gtk_window_set_opacity() calls and did set_app_paintable(True) instead. Since then all transparency was handled by cairo drawing.
https://bazaar.launchpad.net/~onboard/onboard/trunk/revision/2036

This could very well be a bug in Plasma or even Gtk, but I'm wondering what happens if you enable the old override_background_color() calls at
https://bazaar.launchpad.net/~onboard/onboard/trunk/view/2180/Onboard/KbdWindow.py#L205

Could you
sudo gedit /usr/lib/python3/dist-packages/Onboard/KbdWindow.py
and replace line 204
             if gtk_version < Version(3, 18): # Xenial doesn't need them
with
             if True: #gtk_version < Version(3, 18): # Xenial doesn't need them
?

>
> sudo vim /usr/lib/python3.5/site-packages/Onboard/KbdWindow.py

I'm running Manjaro -- a rolling release distro based on Arch. Changing the
file had no effect. FYI, the version of Cairo installed is:

> cairo 1.14.6-2

python2-cairo 1.10.0-6

My GTK is v3.22.1+67+gffb1ac5-1.

Stefan Zecevic
The little commuter in the big red scooter

On Tue, Oct 25, 2016 at 3:10 AM, marmuta <email address hidden> wrote:

> What distribution is this?
>
> There was a change in Onboard in version 1.2 that dropped
> gtk_window_set_opacity() calls and did set_app_paintable(True) instead.
> Since then all transparency was handled by cairo drawing.
> https://bazaar.launchpad.net/~onboard/onboard/trunk/revision/2036
>
> This could very well be a bug in Plasma or even Gtk, but I'm wondering
> what happens if you enable the old override_background_color() calls at
> https://bazaar.launchpad.net/~onboard/onboard/trunk/view/
> 2180/Onboard/KbdWindow.py#L205
>
> Could you
> sudo gedit /usr/lib/python3/dist-packages/Onboard/KbdWindow.py
> and replace line 204
> if gtk_version < Version(3, 18): # Xenial doesn't need them
> with
> if True: #gtk_version < Version(3, 18): # Xenial doesn't
> need them
> ?
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1636252
>
> Title:
> KDE Plasma 5.8 LTS doesn't render transparency effects
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/onboard/+bug/1636252/+subscriptions
>

How does the floating icon look? It has transparency enabled independently of the keyboard.
Check Preferences->General->Show floating icon, then hide the keyboard.

The floating icon looks good. When I move it, the background behind it is redrawn as expected.

Can confirm on Arch with plasma-desktop 5.8.3-1. The floating icon transparency is fine, but the background behind the keyboard doesn't seem to get updated. No problem with Ubuntu's 5.7.5. This might be a kwin issue, but I'm not fully sure.

So this is not a Plasma issue. Same thing happens in gnome-shell. It's caused by the git version of Gtk3 that Arch uses, 3.22.2+4+gc54f348-1 in my case. The people at Plasma IRC kindly pointed me in the right direction.

I've tracked it down to KeyboardWidget.get_xid(). What I think happens is that a native X window is being created inside this call, but isn't initialized properly for transparency. I've attached (Python) sample code that triggers the problem, i.e. the green rectangle ought to be transparent but isn't.

Two preconditions: the top level window must set accept_focus=False, and at any point get_xid() must be called on the GtkDrawingArea child. We can't change the former in Onboard, however there is a workaround for the latter:

Set
Preferences->Keyboard->Advanced->Input event source
to Gtk.

I believe a real fix has to come from Gtk. I'm going to file an upstream bug report, though I fully expect it to be ignored, as usual.

Here's the upstream bug report:
https://bugzilla.gnome.org/show_bug.cgi?id=773821

This bug has arrived in Ubuntu 17.04 with default unity7/compiz and libgtk-3-0 3.22.4.

Finally found a workaround. Upstream bug is still there in Gtk 3.22.7, but it shouldn't affect Onboard anymore.