Always save the window state and geometry
Reimplement KMainWindow::applyMainWindowSettings() to override menubar state
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Rename SaveGeometryOnExit to RememberWindowSize
And migrate the old key name to the new one.
This includes the toolbar/menubar/dockwidget states (i.e. the State= config key), and the window geometry. I was wrong to think the State= key included the window geometry.
Depending on the "remeber window size" setting, we can apply the size saved in the config file or the size from the profile settings (lines x columns), which is included in MainWindow::sizeHint().
BUG: 442252 FIXED-IN: 21.12