comctl32: header: Send the width in HDN_BEGINTRACK.

dlls/comctl32/header.c

diff --git a/dlls/comctl32/header.c b/dlls/comctl32/header.c
index 4dec2d7..19d3889 100644
--- a/dlls/comctl32/header.c
+++ b/dlls/comctl32/header.c
@@ -1465,7 +1465,7 @@
 	TRACE("Pressed item %d!\n", nItem);
     }
     else if ((flags == HHT_ONDIVIDER) || (flags == HHT_ONDIVOPEN)) {
-        if (!(HEADER_SendHeaderNotifyT (hwnd, HDN_BEGINTRACKW, nItem, 0, NULL))) {
+        if (!(HEADER_SendHeaderNotifyT (hwnd, HDN_BEGINTRACKW, nItem, HDI_WIDTH, NULL))) {
 	    SetCapture (hwnd);
 	    infoPtr->bCaptured = TRUE;
 	    infoPtr->bTracking = TRUE;