--- kwin/geometry.cpp.sav	2006-08-18 15:33:22.000000000 +0200
+++ kwin/geometry.cpp	2006-08-30 19:08:27.000000000 +0200
@@ -1722,6 +1722,7 @@ void Client::setGeometry( int x, int y, 
     sendSyntheticConfigureNotify();
     updateWindowRules();
     checkMaximizeGeometry();
+    workspace()->checkActiveScreen( this );
     }
 
 void Client::plainResize( int w, int h, ForceGeometry_t force )
@@ -1775,6 +1776,7 @@ void Client::plainResize( int w, int h, 
     sendSyntheticConfigureNotify();
     updateWindowRules();
     checkMaximizeGeometry();
+    workspace()->checkActiveScreen( this );
     }
 
 /*!
@@ -1795,6 +1797,7 @@ void Client::move( int x, int y, ForceGe
     sendSyntheticConfigureNotify();
     updateWindowRules();
     checkMaximizeGeometry();
+    workspace()->checkActiveScreen( this );
     }
 
 
--- kwin/workspace.cpp.sav	2006-06-23 14:35:28.000000000 +0200
+++ kwin/workspace.cpp	2006-08-30 19:46:15.000000000 +0200
@@ -1526,6 +1526,18 @@ int Workspace::activeScreen() const
     return qApp->desktop()->screenNumber( QCursor::pos());
     }
 
+// check whether a client moved completely out of what's considered the active screen,
+// if yes, set a new active screen
+void Workspace::checkActiveScreen( const Client* c )
+    {
+    if( !options->xineramaEnabled )
+        return;
+    if( !c->isActive())
+        return;
+    if( !c->isOnScreen( active_screen ))
+        active_screen = c->screen();
+    }
+
 QRect Workspace::screenGeometry( int screen ) const
     {
     if( !options->xineramaEnabled )
@@ -1555,6 +1567,8 @@ void Workspace::sendClientToScreen( Clie
          it != transients_stacking_order.end();
          ++it )
         sendClientToScreen( *it, screen );
+    if( c->isActive())
+        active_screen = screen;
     }
 
 void Workspace::setDesktopLayout(int o, int x, int y)
--- kwin/workspace.h.sav	2006-06-23 14:35:28.000000000 +0200
+++ kwin/workspace.h	2006-08-30 19:08:43.000000000 +0200
@@ -166,6 +166,7 @@ class Workspace : public QObject, public
         
         int activeScreen() const;
         int numScreens() const;
+        void checkActiveScreen( const Client* c );
         QRect screenGeometry( int screen ) const;
         int screenNumber( QPoint pos ) const;