DDWM_UPDATEWINDOW message

Instructs a drop image window to update using new DROPDESCRIPTION information.

Parameters

• wParam [in]
  Not used.

• lParam [in]
  Not used.

Remarks

DDWM_UPDATEWINDOW is defined as WM_USER+3.

When the state of a drop operation changes—such as in response to a modifier key—IDropTarget::DragOver returns a new DROPEFFECT value (this DROPEFFECT value can also be received through IDropSource::GiveFeedback). In response, the application updates the drop target's DROPDESCRIPTION structure with a new DROPIMAGETYPE value that indicates the decoration to be applied to the drag window's visual; for instance, an indication that the file is being copied rather than moved or that the object cannot be dropped to that location. However, the visuals are not updated until the object receives a DDWM_UPDATEWINDOW message.

The DragWindow clipboard format provides the HWND of the recipient drag window to the sender of the DDWM_UPDATEWINDOW message.

Requirements