Vertical and Horizontal DD Layouts cannot handle child Vertical or Horizontal layouts

[TDHewson]

I encountered and issue whereby a DDVerticalLayout I was using contained components that had VerticalLayouts (not the dragdrop variants) within them. Whenever a drag operation was made, the client component would attempt determine the index of the drop area; in doing this, it would allocate the Slot object of the sub-VerticalLayout as the drop component and - because the sub-VerticalLayout was not a component of the DDVerticalLayout) - it would resolve the drop component as the DDVerticalLayout with a dropIndex of -1.

Attached is a demonstration class to show this (it will need to become a .java file and be added to a UI); using this code I was unable to drag number 3 between number 1 and 2 - it would always be determined on the client side to be at the top of the container.

DDVerticalLayoutTest.txt

The same behaviour occurs with HorizontalLayouts - it's the underlying Slot class (common to both Vertical and HorizontalLayouts) that is discovered in the client code (VDDVerticalLayoutDropHandler).

[a-schild]

@TDHewson when I do the test with the DefaultVerticalLayoutDropHandler which is included, I'm able to drop the components at the correct places.