DL_BEGINDRAG Overview Group

The DL_BEGINDRAG notification message notifies the parent window of a drag list box that the user has clicked the left mouse button on a list item. A drag list box sends DL_BEGINDRAG in the form of a drag list message.

DL_BEGINDRAG 
idCtl = (int) wParam; 
pDragInfo = (LPDRAGLISTINFO) lParam; 
 

Parameters

idCtl

Control identifier of the drag list box.

pDragInfo

Pointer to a DRAGLISTINFO structure that contains the DL_BEGINDRAG notification code, the handle to the drag list box, and the cursor position.

Return Values

The parent window should return TRUE to begin a drag operation or FALSE to prevent a drag operation.

Remarks

When processing this notification message, a window procedure typically determines the list item at the specified cursor position by using the LBItemFromPt function and then returns TRUE or FALSE, depending on whether the item should be dragged. Before returning TRUE, the window procedure should save the index of the list item, so the application knows which item to move or copy when the drag operation is completed.

See Also

DRAGLISTINFO, LBItemFromPt

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