Kwin window over both monitors

Question

How can I make a window span over both monitors? I have the monitors configured using the KDE monitor setting tool. I need specifically full-screen (for presentation purposes) or at least a maximized window. Kwin insists on locking the window on one desktop.

Edit: interestingly it really is Kwin preventing me to do this. If I get rid of KDE and just launch a plain X session, the window maximizes correctly.

Answer 1

Disable Enable multiple monitor window fullscreen support & Enable multiple monitor window maximize support in System Settings > Display > Multiple Monitors (the 'support' being that it will only maximize/fullscreen on 1 monitor, instead of the 'default' complete virtual desktop which seems to be what you want).

Answer 2

It would seem that this isn't possible anymore. The settings that previously allowed this in System > Display > Multiple Monitors are not there anymore in newer versions.