diff -r dee5afe5301f -r 3f74d0d4af4c src/gui/kernel/qtooltip.cpp
--- a/src/gui/kernel/qtooltip.cpp	Mon Mar 15 12:43:09 2010 +0200
+++ b/src/gui/kernel/qtooltip.cpp	Thu Apr 08 14:19:33 2010 +0300
@@ -368,7 +368,16 @@
 
 
 #ifdef Q_WS_MAC
-    QRect screen = QApplication::desktop()->availableGeometry(getTipScreen(pos, w));
+    // When in full screen mode, there is no Dock nor Menu so we can use
+    // the whole screen for displaying the tooltip. However when not in
+    // full screen mode we need to save space for the dock, so we use
+    // availableGeometry instead.
+    extern bool qt_mac_app_fullscreen; //qapplication_mac.mm
+    QRect screen;
+    if(qt_mac_app_fullscreen)
+        screen = QApplication::desktop()->screenGeometry(getTipScreen(pos, w));
+    else
+        screen = QApplication::desktop()->availableGeometry(getTipScreen(pos, w));
 #else
     QRect screen = QApplication::desktop()->screenGeometry(getTipScreen(pos, w));
 #endif