RATIONAL It is hard to discover how to toggle on/off an application in fullscreen mode. PROPOSAL For the applications that support fullscreen, an icon is displayed in the titlebar for toggle on this mode. In fullscreen mode, a fake title bar appears when the cursor hit the top of the screen. This fake titlebar has an icon for toggle off fullscreen mode. RELATED ISSUES https://bugs.kde.org/show_bug.cgi?id=413255 https://bugs.kde.org/show_bug.cgi?id=177094 PREVIOUS ART fullscreen mode on macos: https://www.youtube.com/watch?time_continue=19&v=EbkbaQDFQ9U&feature=emb_logo
Already reported as Bug 419122.