Added rect_in_region function.

diff --git a/server/user.h b/server/user.h
index 638ffc6..7f510ee 100644
--- a/server/user.h
+++ b/server/user.h
@@ -84,6 +84,7 @@
 extern struct region *union_region( struct region *dst, const struct region *src1,
                                     const struct region *src2 );
 extern int point_in_region( struct region *region, int x, int y );
+extern int rect_in_region( struct region *region, const rectangle_t *rect );
 static inline struct region *create_empty_region(void) { return create_region( NULL, 0 ); }
 
 /* window functions */