--- a/WindowSensor.st	Thu Dec 23 17:27:47 1999 +0100
+++ b/WindowSensor.st	Thu Dec 23 20:08:07 1999 +0100
@@ -2903,9 +2903,11 @@
                  To not block forever, we wait with a timeout, to get out of here
                  if the event does not arrive after a few seconds.
                 "
-                (exposeEventSemaphore waitWithTimeout:(pollDelay2 * lostExpose)) isNil ifTrue:[
-                    device flush.         "/ we are paranoid
-                    lostExpose := lostExpose + 1.
+                exposeEventSemaphore notNil ifTrue:[
+                    (exposeEventSemaphore waitWithTimeout:(pollDelay2 * lostExpose)) isNil ifTrue:[
+                        device flush.         "/ we are paranoid
+                        lostExpose := lostExpose + 1.
+                    ]
                 ].
             ].
             (gotExpose includes:aView) ifFalse:[
@@ -2935,7 +2937,7 @@
     ].
 
     "Modified: / 20.2.1997 / 09:24:31 / stefan"
-    "Modified: / 14.12.1999 / 20:58:33 / cg"
+    "Modified: / 23.12.1999 / 20:07:28 / cg"
 !
 
 waitNoButton
@@ -2953,6 +2955,6 @@
 !WindowSensor class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libview/WindowSensor.st,v 1.172 1999-12-14 20:14:22 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libview/WindowSensor.st,v 1.173 1999-12-23 19:08:07 cg Exp $'
 ! !
 WindowSensor initialize!