use the same arrow in drawer-window

for a better viewing and more accessability i would recommend to use the arrow which is used if right-clicking on a drawer to indicate which icon was clicked also for the drawer window when it is opened so one could see at first sight which window is opend.
and for my personal view it also looks better ;-)

[icb410] This was discussed previously in one of the bug report feature requests. The problem occurs that in some cases you might have a drawer that is not attached to the Unity Launcher. Then the arrow would point to nothing.

[Jan Schürmann] OK, but how does it work with the right-click menu opened from launcher? there it seems to work. could you implement that code in the window code? i'm not a programmer, so i don't know if thats possible...