Slider does not receive focus when dragging handle

[dante]

When you click the handle and start dragging, focus should be placed on the slider handle.

[dante]

duplicate of #4754

[bill]

This really isn't a duplicate. The slider handle and the slider bar are two different things. The bar is the long skinny thing.

[dante]

iirc you have the rest of the slider focus tickets. thought i'd already reassigned this .

[Becky Gibson]

Using MS Inspect, it appears that the slider IS getting focus - but the focus style is not getting applied.

[Douglas Hays]

(In [11054]) Fixes #4751. Focus state was only being set the first time the bar was clicked.