change prototype of __mg_do_change_topmost_layer: change mgTopmostLayer in __mg_do_change_topmost_layer function

src/include/server.h

@@ -159,7 +159,7 @@ int __mg_prepare_layer_for_compositing (MG_Layer* layer);
 int __mg_end_up_layer_for_compositing (MG_Layer* layer);
 #endif
 
-int __mg_do_change_topmost_layer (void);
+int __mg_do_change_topmost_layer (MG_Layer* new_topmost);
 
 MG_Layer* __mg_find_layer_by_name (const char* name);
 

src/server/layer.c

@@ -628,10 +628,9 @@ BOOL GUIAPI ServerSetTopmostLayer (MG_Layer* layer)
     DO_COMPSOR_OP_ARGS (transit_to_layer, layer);
 #endif
 
-    mgTopmostLayer = layer;
     CHANGE_TOPMOST_LAYER (layer);
 
-    __mg_do_change_topmost_layer ();
+    __mg_do_change_topmost_layer (layer);
 
 #ifdef _MGSCHEMA_COMPOSITING
     if (old_topmost) {