Windows Forms User's Guide > Howto: Drag and Drop Files
Three .NET events are involved when implementing File Drag and Drop:
If you drop a file on the text window, these events will occur in TX Text Control. However, if the file is dropped outside of TX Text Control's bounds, e.g. on the application's toolbar, the events will occur in the application's form. This offers the opportunity to provide different actions, depending on where exactly a file is dropped. Microsoft Word 2007(R), for instance, will load a file that is dropped onto its toolbars, but not if dropped onto the text area.