Canceling a Drag Operation

The user can end a direct manipulation operation in one of the three following ways:

• Pressing the Esc key to cancel the operation

• Releasing the drag button when the pointer is over a target that cannot accept the drop

  This action is equivalent to pressing the Esc key. When the pointer is over a target that can accept the drop, the target is informed of the drop, and the source is given the window handle of the target.

• Pressing the F1 key to request help

  A DM_DROPHELP message is posted to the target. This enables the target to provide the user with assistance regarding:

  • What would happen if the user dropped the object on that target
    
  • Why the target cannot accept a particular drop
  The source sees this termination of the direct manipulation operation as a cancelation.