Add better error check for 'window' word

diff --git a/basis/ui/ui.factor b/basis/ui/ui.factor
index dff7726d0850294da67174e6a9d558db18592495..1de3912f2861beb3df299ff184e106a3ef86f07c 100644 (file)
--- a/basis/ui/ui.factor
+++ b/basis/ui/ui.factor
@@ -12,7 +12,10 @@ IN: ui
 ! Assoc mapping aliens to gadgets
 SYMBOL: windows
 
-: window ( handle -- world ) windows get-global at ;
+ERROR: no-window handle ;
+
+: window ( handle -- world )
+    windows get-global ?at [ no-window ] unless ;
 
 : window-focus ( handle -- gadget ) window world-focus ;