restore click and hover effect

wanted behaviour: when clicking on the menu, the subnavigation appears. Hovering to another menu entry so opens the according sub navigation similar to apple's menu bar
fix an issue with border line

the submenu has a 2 pixel border, this should be only one pixel
fix issue with clipboard height

item collapsed if border box was active
fix for issue #3413
fix for issue #3316
restore tabs
correct fix for #3316
first commit for fixing #3111
Fix placeholderadmin permission check
Merge pull request #3615 from FinalAngel/support/fe-fixes

Some frontend cleanup
ensure maximize button is hidden when minimizing
fix an issue where maximized window shows minimized
Fix title cursor when maximized
fixed cursor when minimized
fix an issue where modal behaves weird when minimized and closed
use tabs not spaces
also ensure this works on maximize
added additional comment
Merge pull request #3617 from yakky/feature/backport_3610

Fix placeholderadmin permission check
noConflict not required

needs more testing