Colorselector: Item Selection/Unselection logic changes and corresponding API additions.

Colorselector: Item Selection/Unselection logic changes and corresponding API additions.

SUMMARY
Item should remain selected once pressed.
When one item is selected other items should be unselected.
No special behavior on long press, item gets selected on mouse up.
APIs added are to get current selected item and to programmatically
control the selection/unselection of an item.

This is patch D515 (had to do by hand).