dispatch just the relevant key/mouse events

get rid of screenshots by always using and painting a separate native window

fix RegexpFilterTest: ApplicationManager.getApplication() is unavailable in tests not implementing PlatformTestCase (IDEA-CR-16529)

IDEA-101953 File not showing under project pane / Missing files (blank entries) in project view after the "Mark As ..." action

mem leaks: clear CWindow listeners and rootPane: drop glass/content pane cleanup and see how it goes

* do not remember derived sizes -> it's rarely needed and
 it's better to use preferred width;