[Development] KDE ColorScheme change notifications on DBus

[Axel Spoerl]

Good morning,

this is a call to KDE experts on this line.

In order to react to KDE color scheme changes, Qt listens to DBus for changes (under more) of the keys

  *   "ColorScheme" in org.kde.kdeglobals.General
  *   "widgetStyle" in org.kde.kdeglobals.KDE

A DBus signal correctly received and processed by Qt would look like that:

---snip---
method return time=1682062165.741561 sender=org.freedesktop.DBus -> destination=:1.87 serial=50 reply_serial=89
signal time=1682062165.742192 sender=:1.28 -> destination=(null destination) serial=38 path=/org/freedesktop/portal/desktop; interface=org.freedesktop.impl.portal.Settings; member=Setting
Changed
  string "org.kde.kdeglobals.General"
  string "ColorScheme"
  variant       string "BreezeLight"
---snap---

On some systems, however, none of signals mentioned gets emitted. As a consequence, Qt doesn't notify its applications: https://bugreports.qt.io/browse/QTBUG-103093
=> I fail to reproduce the bug, so I can only assume that it a local configuration issue (e.g. Plasma only installation).
=> OTOH I can't find the spot in the KDE documentaiton, where it is defined how to reliably subscribe to changes of color scheme, widget style and the like.

Questions:
a) In which cases are the mentioned DBus emitted or not?
b) Could you point me at the respective spot in the KDE documentation?

Thanks and brgds
axel
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/development/attachments/20230425/0f646c9c/attachment.htm>