The drag and drop helpers are mainly used for providing visual feedback for drag and drop operations. While they do not actually influence the dragging process, some applications may expect it to succeed before initiating dragging. If the functions are not implemented, however, then dragging may fail.
This patch set contains tests for basic functionality of the functions involved. It does not account for displaying the drag-image, it just tests for enough functionality to create a basic implementation and allow dragging operations to carry on. Drag-image handling will be added later.
The patch set contains only the tests. The implementation will be added in a separate MR.
-- v5: shell32/tests: Add tests for drag and drop helpers include/shlobj.h: Add DI_GETDRAGIMAGE message include/shobjidl.idl: Add DSH_ALLOWDROPDESCRIPTIONTEXT constant