Fix off by one error in HEADER_InsertItemW.

dlls/comctl32/header.c

@@ -958,6 +958,12 @@ HEADER_InsertItemW (HWND hwnd, WPARAM wParam, LPARAM lParam)
 
         infoPtr->uNumItem++;
         infoPtr->items = COMCTL32_Alloc (sizeof (HEADER_ITEM) * infoPtr->uNumItem);
+        if (nItem == 0) {
+            memcpy (&infoPtr->items[1], &oldItems[0],
+                    (infoPtr->uNumItem-1) * sizeof(HEADER_ITEM));
+        }
+        else
+        {
               /* pre insert copy */
             if (nItem > 0) {
                  memcpy (&infoPtr->items[0], &oldItems[0],
@@ -967,7 +973,8 @@ HEADER_InsertItemW (HWND hwnd, WPARAM wParam, LPARAM lParam)
             /* post insert copy */
             if (nItem < infoPtr->uNumItem - 1) {
                 memcpy (&infoPtr->items[nItem+1], &oldItems[nItem],
-                    (infoPtr->uNumItem - nItem) * sizeof(HEADER_ITEM));
+                        (infoPtr->uNumItem - nItem - 1) * sizeof(HEADER_ITEM));
+            }
         }
     
         COMCTL32_Free (oldItems);
@@ -998,6 +1005,10 @@ HEADER_InsertItemW (HWND hwnd, WPARAM wParam, LPARAM lParam)
     if (lpItem->fmt == 0)
 	lpItem->fmt = HDF_LEFT;
 
+    if (!(lpItem->fmt &HDF_STRING) && (phdi->mask & HDI_TEXT))
+      {
+	lpItem->fmt |= HDF_STRING;
+      }
     if (phdi->mask & HDI_BITMAP)
         lpItem->hbm = phdi->hbm;