Created attachment 155365 [details] How popups look in normal QT apps (with transparency enabled in settings) SUMMARY Kirigami application popup menus are highly inconsistent with QT apps & look ugly on desktops. Normal QT app's popups have a little amount of padding & their transparency can be tweaked by the global theme settings, which look good with a blur effect. But Kirigami apps do not use that theme & default to an opaque style by default with more padding. Another problem is that popups should close on clicking outside the application, but this is not the case with Kirigami-based popups. STEPS TO REPRODUCE 1. Open any QT-based app (like Dolphin). 2. Open any Kirigami-based app (like System Monitor). 3. Click on the menu icons & compare the popup menu differences. OBSERVED RESULT The popups look highly inconsistent EXPECTED RESULT Kirigami-based popups should respect the application theme (transparency, blur & padding) & should close on clicking outside the application window. SOFTWARE/OS VERSIONS Linux/KDE Plasma: 5.15.88-1-lts (64-bit) KDE Plasma Version: 5.26.5 KDE Frameworks Version: 5.102.0 Qt Version: 5.15.8
Created attachment 155366 [details] How popups look in Kirigami apps (no background transparency)
Created attachment 155379 [details] Kirigami popups do not close on clicking outside the window
I'm afraid this is the way menus are implemented in QtQuickControls, which is the Qt UI toolkit that Kirigami is based on. Ultimately it's not something we can fix in KDE code; QQC itself needs to be changed to implement menus as separate windows that can be independently styled and themed by the app style and compositor, as in QtWidgets. I do agree with you that this would be desirable, in general.
To my knowledge, plasmashell uses QML. But it has traditional popup menus. So it seems not impossible to implement them for Kirigami apps too.
Yes, each individual app can manually create C++ QMenus, invoked from QML. It's a bug pain though and not really a generic solution.