From Xojo Documentation
Permits pictures to be dropped on the control. Use this method to accept pictures dropped directly from another application such as a web browser. If you want to accept pictures that come from the file system (using Finder or Windows Explorer) you need to use AcceptFileDrop.
If a control should accept pictures in a drag and drop, then AcceptPictureDrop needs to be called prior to the drop. Typically, it is in the Open event of the control itself. For example, the line:
in the Open event of the control that will receive the dragged pictures is needed. When the picture is dropped, the DropObject event is called and this is where you will put your code to handle the drop.