Update _bugfixClickTime only if it is not null.
Fix: if a theme shows icon for Activities, that icon is shown when Activities is off, HotCorner is on.
Additional checks with _bugfixClickTime.
Consider window focused when its transient is focused only if showing interesting windows is on.
Fix: change transient windows minimize state when main window changes its minimize state.
activateWindow and minimizeWindow functions moved to Tracker to take care of transient windows.