DL_BEGINDRAG
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