Force recalculation of menu when calling InsertMenuItem.

diff --git a/controls/menu.c b/controls/menu.c
index f3a1dfb..bfa5196 100644
--- a/controls/menu.c
+++ b/controls/menu.c
@@ -1822,6 +1822,7 @@
     menu->items = newItems;
     menu->nItems++;
     memset( &newItems[pos], 0, sizeof(*newItems) );
+    menu->Height = 0; /* force size recalculate */
     return &newItems[pos];
 }