#666 Fix for bug #4563 Tab bar bug

[Gur Stavi]

For Windows Tab control when working in multiline mode and selecting a tab the line containing it is automatically moved down. The mouse continue to point to the upper line so immediately there is additional switch and flickering happens.

The fix removes tab selection during drag. Selection only happens after mouse up event.
In addition redraw takes into account dragging mode. While dragging a tab the dragged tab is treated as selected.