Draw drag header - windows zoom

[ElRicoB21]

Draw drag a header when using Windows zoom (Win 10, zoom by combo items) is Incorrect. See video attachment.

DragHeader.mp4

[livius2]

Hi, isn't this issue with zoom itself?

[joachimmarder]

While during drag&drop of nodes VTV lets the system do the drawing of the drag image (via IDataObject and IDragSourceHelper), during header drag the VTV control does the drawing on its own. So some dummy IDataObject could improve the situation and allow us to eliminate those old code paths.
Methods to look into:

• TVTDragImage.PrepareDrag()
• TVTHeader.DragTo()
• TBaseVirtualTree.UpdateWindowAndDragImage()

Issue #1138 was created to prepare for this issue.