Correctly handle left-click on toolbar (and status bar) button
(regression in 53c043e03634efcdaa3d1bdb3732d8edea57b1b1 commit)
Update prefs "library": add ability to handle default branch
Use undoable way to reset controls behavior
Old: reset => changed and saved
New: reset => changed, apply => saved
Controls behavior: disable reset buttons on current state basis