flagsImGuiDragDropFlags options controlling this operation; combine compatible flag bits with |.
True while this item is an active drag source and may submit its payload/preview. Call EndDragDropSource() only when true.
On source items, call BeginDragDropSource(), if it returns true also call SetDragDropPayload() + EndDragDropSource().
On target candidates, call BeginDragDropTarget(), if it returns true also call AcceptDragDropPayload() + EndDragDropTarget().
If you stop calling BeginDragDropSource() the payload is preserved however it won't have a preview tooltip (we currently display a fallback "..." tooltip, see #1725)
An item can be both drag source and drop target.
call after submitting an item which may be dragged. when this return true, you can call SetDragDropPayload() + EndDragDropSource()
Begin a drag-and-drop source.