Used to be that with quick-maximize off, dragging a maximized window to a different screen would make it jump to the other screen while remaining maximized. Now, when using the modifier (alt/super), the window remains in a maximized state (screen-sized and no borders) but behaves like a regular window, which looks extremely broken. When dragging with the mouse, the window unmaximizes and loses focus, which is even more broken. Reproducible: Always
Not reproducible here. What happens (and is intended) is that you start dragging the maximized window (it remains maximized) and when dropping it on another screen, it gets a geometry correction on that screen (what's like the behavior kwin ever had except that you now see that the window is moved and it doesn't suddenly jump over after apparently not reacting) => please attach the output of "qdbus org.kde.KWin /KWin supportInformation" and notably check the "electricBorderMaximize" setting.
I can't seem to find an option for quick maximize on the current Window Rules and Window Behavior KCMs. Has this been removed with the new Window Rules KCM? From the description provided by Unknown, what they want sounds precisely the same as the behavior of moving fullscreen windows between screens.
This doesn't seem to be related to Window Rules, but a more general issue related to multi-screen behavior. Moving it to multi-screen component.
This bug was reported against an outdated version of KWin. We have made many changes since the. If the issue persists in newer versions can you reopen the bug report updating the version number.