HiDPI: TabBar resizer changes size depending on DPI scale factor

Change-Id: I36a6d22f87b0d96cdbdadd683cd3abeb12e28c77
Rework TabBar D&D tab move triangles and make them HiDPI aware

Change-Id: Ia4165880b0b08b5ca26fe7004f961cd17b3d3e27