diff --git a/effects/CMakeLists.txt b/effects/CMakeLists.txt
index a65c689cb0..30715002d0 100644
--- a/effects/CMakeLists.txt
+++ b/effects/CMakeLists.txt
@@ -13,6 +13,7 @@ include_directories(
 SET(kwin4_effect_builtins_sources
     boxswitch.cpp
     desktopchangeslide.cpp
+    desktopgrid.cpp
     dialogparent.cpp
     diminactive.cpp
     drunken.cpp
@@ -73,6 +74,7 @@ KWIN4_ADD_EFFECT(tests ${kwin4_effect_tests_sources})
 install( FILES
     boxswitch.desktop
     desktopchangeslide.desktop
+    desktopgrid.desktop
     dialogparent.desktop
     diminactive.desktop
     drunken.desktop
diff --git a/effects/desktopgrid.cpp b/effects/desktopgrid.cpp
new file mode 100644
index 0000000000..c50c732241
--- /dev/null
+++ b/effects/desktopgrid.cpp
@@ -0,0 +1,133 @@
+/*****************************************************************
+ KWin - the KDE window manager
+ This file is part of the KDE project.
+
+Copyright (C) 2007 Lubos Lunak <l.lunak@kde.org>
+
+You can Freely distribute this program under the GNU General Public
+License. See the file "COPYING" for the exact licensing terms.
+******************************************************************/
+
+#include "desktopgrid.h"
+
+#include <kaction.h>
+#include <kactioncollection.h>
+#include <klocale.h>
+
+namespace KWin
+{
+
+KWIN_EFFECT( DesktopGrid, DesktopGridEffect )
+
+DesktopGridEffect::DesktopGridEffect()
+    : progress( 0 )
+    , activated( false )
+    {
+    KActionCollection* actionCollection = new KActionCollection( this );
+    KAction* a = static_cast< KAction* >( actionCollection->addAction( "ShowDesktopGrid" ));
+    a->setText( i18n("Show Desktop Grid" ));
+    a->setGlobalShortcut( KShortcut( Qt::CTRL + Qt::Key_F8 ));
+    connect( a, SIGNAL( triggered( bool )), this, SLOT( toggle()));
+    }
+
+void DesktopGridEffect::prePaintScreen( int* mask, QRegion* region, int time )
+    {
+    if( progress != 0 || activated )
+        {
+        if( activated )
+            progress = qMin( 1.0, progress + time / 500. );
+        else
+            progress = qMax( 0.0, progress - time / 500. );
+        // PAINT_SCREEN_BACKGROUND_FIRST is needed because screen will be actually painted more than once,
+        // so with normal screen painting second screen paint would erase parts of the first paint
+        if( progress != 0 )
+            *mask |= PAINT_SCREEN_TRANSFORMED | PAINT_SCREEN_BACKGROUND_FIRST;
+        }
+    effects->prePaintScreen( mask, region, time );
+    }
+
+void DesktopGridEffect::prePaintWindow( EffectWindow* w, int* mask, QRegion* paint, QRegion* clip, int time )
+    {
+    if( progress != 0 )
+        {
+        if( w->isOnDesktop( painting_desktop ))
+            w->enablePainting( EffectWindow::PAINT_DISABLED_BY_DESKTOP );
+        else
+            w->disablePainting( EffectWindow::PAINT_DISABLED_BY_DESKTOP );
+        }
+    effects->prePaintWindow( w, mask, paint, clip, time );
+    }
+
+void DesktopGridEffect::paintScreen( int mask, QRegion region, ScreenPaintData& data )
+    {
+    if( progress == 0 )
+        {
+        effects->paintScreen( mask, region, data );
+        return;
+        }
+    for( int desktop = 1;
+         desktop <= effects->numberOfDesktops();
+         ++desktop )
+        {
+        QRect rect = desktopRect( desktop, true );
+        if( region.contains( rect )) // this desktop needs painting
+            {
+            painting_desktop = desktop;
+            ScreenPaintData d = data;
+            QRect normal = desktopRect( effects->currentDesktop(), false );
+            d.xTranslate += rect.x(); // - normal.x();
+            d.yTranslate += rect.y(); // - normal.y();
+            d.xScale *= rect.width() / float( normal.width());
+            d.yScale *= rect.height() / float( normal.height());
+            // TODO mask parts that are not visible?
+            effects->paintScreen( mask, region, d );
+            }
+        }
+    }
+
+void DesktopGridEffect::postPaintScreen()
+    {
+    if( activated ? progress != 1 : progress != 0 )
+        effects->addRepaintFull(); // trigger next animation repaint
+    effects->postPaintScreen();
+    }
+
+// Gives a position of the given desktop when all desktops are arranged in a grid
+QRect DesktopGridEffect::desktopRect( int desktop, bool scaled )
+    {
+    int x, y;
+    Qt::Orientation orientation;
+    effects->calcDesktopLayout( &x, &y, &orientation );
+    --desktop; // make it start with 0
+    QRect rect;
+    if( orientation == Qt::Vertical )
+        rect = QRect(( desktop % x ) * displayWidth(), ( desktop / x ) * displayHeight(),
+            displayWidth(), displayHeight());
+    else
+        rect = QRect(( desktop / y ) * displayWidth(), ( desktop % y ) * displayHeight(),
+            displayWidth(), displayHeight());
+    if( !scaled )
+        return rect;
+    QRect current = desktopRect( effects->currentDesktop(), false );
+    rect = QRect( int( interpolate( rect.x() - current.x(), rect.x() / float( x ), progress )),
+        int( interpolate( rect.y() - current.y(), rect.y() / float( y ), progress )),
+        int( interpolate( rect.width(), displayWidth() / float( x ), progress )),
+        int( interpolate( rect.height(), displayHeight() / float( y ), progress )));
+    return rect;
+    }
+
+void DesktopGridEffect::desktopChanged( int )
+    {
+    if( activated )
+        toggle();
+    }
+
+void DesktopGridEffect::toggle()
+    {
+    activated = !activated;
+    effects->addRepaintFull();
+    }
+
+} // namespace
+
+#include "desktopgrid.moc"
diff --git a/effects/desktopgrid.desktop b/effects/desktopgrid.desktop
new file mode 100644
index 0000000000..93dc16f5a7
--- /dev/null
+++ b/effects/desktopgrid.desktop
@@ -0,0 +1,4 @@
+[Desktop Entry]
+Encoding=UTF-8
+Name=DesktopGrid
+X-KDE-Library=kwin4_effect_builtins
diff --git a/effects/desktopgrid.h b/effects/desktopgrid.h
new file mode 100644
index 0000000000..f196c83f5a
--- /dev/null
+++ b/effects/desktopgrid.h
@@ -0,0 +1,42 @@
+/*****************************************************************
+ KWin - the KDE window manager
+ This file is part of the KDE project.
+
+Copyright (C) 2007 Lubos Lunak <l.lunak@kde.org>
+
+You can Freely distribute this program under the GNU General Public
+License. See the file "COPYING" for the exact licensing terms.
+******************************************************************/
+
+#ifndef KWIN_DESKTOPGRID_H
+#define KWIN_DESKTOPGRID_H
+
+#include <kwineffects.h>
+#include <qobject.h>
+
+namespace KWin
+{
+
+class DesktopGridEffect
+    : public QObject, public Effect
+    {
+    Q_OBJECT
+    public:
+        DesktopGridEffect();
+        virtual void prePaintScreen( int* mask, QRegion* region, int time );
+        virtual void paintScreen( int mask, QRegion region, ScreenPaintData& data );
+        virtual void postPaintScreen();
+        virtual void prePaintWindow( EffectWindow* w, int* mask, QRegion* paint, QRegion* clip, int time );
+        virtual void desktopChanged( int old );
+    private slots:
+        void toggle();
+    private:
+        QRect desktopRect( int desktop, bool scaled );
+        float progress;
+        bool activated;
+        int painting_desktop;
+    };
+
+} // namespace
+
+#endif