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