Platform preferences do not update on newer KDE systems

[Christopher Schnick]

Ok so I tried it again a few times and it seems to be inconsistent 
rather than not working at all. The first few attempts I didn't see 
anything in the logs but after a restart, I can see changes being made 
to the map, but the changes are wrong.

It seems like it always sends the previous theme change updates rather 
than the current change. Since there is no previous theme change when 
doing the first theme change in a session, the first theme change update 
is not sent. When you change the theme the second time in a session, 
JavaFX reports the first change, even if that was made a while ago.

So when you do: Start app with system light mode -> change to dark mode 
-> change to light mode again

You get: No reported change when switching to dark mode -> A reported 
change from light to dark when you actually switch from dark to light 
mode again.

On 16/02/2026 18:49, Michael Strauß wrote:
> Change detection on Linux works by listening to the
> notify::gtk-theme-name signal (in PlatformSupport.h/cpp). The
> g_signal_connect_data documentation states that a warning is emitted
> if a signal name doesn't exist. Do you see anything of that sort in
> the console?
>
>
> On Mon, Feb 16, 2026 at 6:37 PM Christopher Schnick <crschnick at xpipe.io> wrote:
>> I have the problem on 2 separate KDE systems now where the Platform preferences map is not updated at runtime on KDE. The values on startup seem to be correct though.
>>
>> My main testing system is a Debian 13 forky/sid testing system with KDE version 6.5.3 from plasmashell -v.