Open a closed sidebar box and enable droppable/sortable in it when you hover a draggable available widget over it

[ldebrouwer]

At the moment you have to explicitly open a sidebar box to allow it to except available widgets. In my humble opinion this is bad UX and the sidebar box should expand automatically when being hovered over with a draggable and it should accept the draggable to it's containing droppable/sortable as well.

The obstacles to overcome:

• Since the draggable in most cases overlaps the sidebar box when dragging over it ( unless you move really quickly ) it's hard to register a 'mouseenter'. This could be solved by setting the 'cursorAt' option for the draggable.
• Opening a sidebar box is trivial but activating the droppable/sortable only seems to kick in when the draggable has been released.

[ocean90]

With #25952 it's now possible to drop a widget on a closed area. Would be nice to have it open too to place the widget to the correct position.

it's hard to register a 'mouseenter'. T

Maybe hoverIntent can help here.

[ocean90]

Duplicate of #13524.