diff --git a/avr/modules/lcd2/gui2/base/rootwindow.asm b/avr/modules/lcd2/gui2/base/rootwindow.asm
index 976b137..f08e4ab 100644
--- a/avr/modules/lcd2/gui2/base/rootwindow.asm
+++ b/avr/modules/lcd2/gui2/base/rootwindow.asm
@@ -103,6 +103,21 @@ RootWindow_GetApp:
 
 
 
+; ---------------------------------------------------------------------------
+; @routine RootWindow_SetApp @global
+;
+; @param Y        address of widget
+; @return R25:R24 address pointer to GuiApp
+; @clobbers none
+
+RootWindow_SetApp:
+  std Y+ROOTWINDOW_OFFS_GUIAPP_LO, r24
+  std Y+ROOTWINDOW_OFFS_GUIAPP_HI, r25
+  ret
+; @end
+
+
+