diff --git a/COMPOSITE_TODO b/COMPOSITE_TODO
index d630110a13..a4c17fe9ca 100644
--- a/COMPOSITE_TODO
+++ b/COMPOSITE_TODO
@@ -71,6 +71,8 @@ General TODO
 
 * cursorPos() does not work reliably now (not from e.g. timers, it needs events), so it's disabled
 
+* window grouping is not implemented for unmanaged windows (used e.g. by DimInactive)
+
 
 OpenGL TODO
 =================================
@@ -237,3 +239,5 @@ Effects TODO
 +   - something that presents all virtual desktops as being in grid (as in pager)
         and zooms out of the old one and into the new one
     - or whatever
+
+* DimInactive flickers when switching between windows (temporarily no window becomes active)
diff --git a/effects.cpp b/effects.cpp
index 1b33473e61..697db4afa7 100644
--- a/effects.cpp
+++ b/effects.cpp
@@ -12,6 +12,7 @@ License. See the file "COPYING" for the exact licensing terms.
 
 #include "deleted.h"
 #include "client.h"
+#include "group.h"
 #include "workspace.h"
 
 #include "kdebug.h"
@@ -286,6 +287,21 @@ void EffectWindowImpl::disablePainting( int reason )
     sceneWindow()->disablePainting( reason );
     }
 
+void EffectWindowImpl::addRepaint( const QRect& r )
+    {
+    toplevel->addRepaint( r );
+    }
+
+void EffectWindowImpl::addRepaint( int x, int y, int w, int h )
+    {
+    toplevel->addRepaint( x, y, w, h );
+    }
+
+void EffectWindowImpl::addRepaintFull()
+    {
+    toplevel->addRepaintFull();
+    }
+
 int EffectWindowImpl::desktop() const
     {
     return toplevel->desktop();
@@ -304,6 +320,13 @@ QString EffectWindowImpl::caption() const
         return "";
     }
 
+const EffectWindowGroup* EffectWindowImpl::group() const
+    {
+    if( Client* c = dynamic_cast< Client* >( toplevel ))
+        return c->group()->effectGroup();
+    return NULL; // TODO
+    }
+
 bool EffectWindowImpl::isMinimized() const
     {
     if( Client* c = dynamic_cast<Client*>( toplevel ))
@@ -479,5 +502,17 @@ EffectWindow* effectWindow( Scene::Window* w )
     return ret;
     }
 
+//****************************************
+// EffectWindowGroupImpl
+//****************************************
+
+ 
+EffectWindowList EffectWindowGroupImpl::members() const
+    {
+    EffectWindowList ret;
+    foreach( Toplevel* c, group->members())
+        ret.append( c->effectWindow());
+    return ret;
+    }
 
 } // namespace
diff --git a/effects.h b/effects.h
index 784a926376..1ac7a3227e 100644
--- a/effects.h
+++ b/effects.h
@@ -64,6 +64,9 @@ class EffectWindowImpl : public EffectWindow
 
         virtual void enablePainting( int reason );
         virtual void disablePainting( int reason );
+        virtual void addRepaint( const QRect& r );
+        virtual void addRepaint( int x, int y, int w, int h );
+        virtual void addRepaintFull();
 
         virtual bool isDeleted() const;
 
@@ -71,6 +74,7 @@ class EffectWindowImpl : public EffectWindow
         virtual int desktop() const; // prefer isOnXXX()
         virtual bool isMinimized() const;
         virtual QString caption() const;
+        virtual const EffectWindowGroup* group() const;
 
         virtual int x() const;
         virtual int y() const;
@@ -109,6 +113,22 @@ class EffectWindowImpl : public EffectWindow
         Scene::Window* sw; // This one is used only during paint pass.
 };
 
+class EffectWindowGroupImpl
+    : public EffectWindowGroup
+    {
+    public:
+        EffectWindowGroupImpl( Group* g );
+        virtual EffectWindowList members() const;
+    private:
+        Group* group;
+    };
+
+inline
+EffectWindowGroupImpl::EffectWindowGroupImpl( Group* g )
+    : group( g )
+    {
+    }
+
 EffectWindow* effectWindow( Toplevel* w );
 EffectWindow* effectWindow( Scene::Window* w );
 
diff --git a/effects/CMakeLists.txt b/effects/CMakeLists.txt
index f444ff413c..99c4cc6303 100644
--- a/effects/CMakeLists.txt
+++ b/effects/CMakeLists.txt
@@ -11,7 +11,7 @@ include_directories(
     ${CMAKE_SOURCE_DIR}/workspace/kwin/lib
     )
 
-KWIN4_ADD_EFFECT(builtins presentwindows.cpp shadow.cpp)
+KWIN4_ADD_EFFECT(builtins presentwindows.cpp shadow.cpp diminactive.cpp)
 
-install( FILES presentwindows.desktop shadow.desktop
+install( FILES presentwindows.desktop shadow.desktop diminactive.desktop
         DESTINATION ${DATA_INSTALL_DIR}/kwin/effects )
diff --git a/effects/diminactive.cpp b/effects/diminactive.cpp
new file mode 100644
index 0000000000..17c0a17c83
--- /dev/null
+++ b/effects/diminactive.cpp
@@ -0,0 +1,76 @@
+/*****************************************************************
+ 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 "diminactive.h"
+
+namespace KWin
+{
+
+KWIN_EFFECT( DimInactive, DimInactiveEffect )
+
+DimInactiveEffect::DimInactiveEffect()
+    : active( NULL )
+    {
+    dim_panels = true; // TODO config option
+    dim_by_group = true; // TODO config option
+    }
+
+void DimInactiveEffect::paintWindow( EffectWindow* w, int mask, QRegion region, WindowPaintData& data )
+    {
+    bool dim = false;
+    if( active == NULL )
+        dim = true;
+    else if( dim_by_group && active->group() == w->group())
+        dim = false;
+    else if( !dim_by_group && active == w )
+        dim = false;
+    else if( w->isDock())
+        dim = dim_panels;
+    else
+        dim = true;
+    if( dim )
+        {
+        data.brightness *= 0.75;
+        data.saturation *= 0.75;
+        }
+    effects->paintWindow( w, mask, region, data );
+    }
+
+void DimInactiveEffect::windowActivated( EffectWindow* w )
+    {
+    if( active != NULL )
+        {
+        if( dim_by_group )
+            {
+            if(( w == NULL || w->group() != active->group()) && active->group() != NULL )
+                { // repaint windows that are not longer in active group
+                foreach( EffectWindow* tmp, active->group()->members())
+                    tmp->addRepaintFull();
+                }
+            }
+        else
+            active->addRepaintFull();
+        }
+    active = w;
+    if( active != NULL )
+        if( dim_by_group )
+            {
+            if( active->group() != NULL )
+                { // repaint newly active windows
+                foreach( EffectWindow* tmp, active->group()->members())
+                    tmp->addRepaintFull();
+                }
+            }
+        else
+            active->addRepaintFull();
+    }
+
+} // namespace
diff --git a/effects/diminactive.desktop b/effects/diminactive.desktop
new file mode 100644
index 0000000000..ea4a923b38
--- /dev/null
+++ b/effects/diminactive.desktop
@@ -0,0 +1,4 @@
+[Desktop Entry]
+Encoding=UTF-8
+Name=DimInactive
+X-KDE-Library=kwin4_effect_builtins
diff --git a/effects/diminactive.h b/effects/diminactive.h
new file mode 100644
index 0000000000..cca9355433
--- /dev/null
+++ b/effects/diminactive.h
@@ -0,0 +1,36 @@
+/*****************************************************************
+ 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_DIMINACTIVE_H
+#define KWIN_DIMINACTIVE_H
+
+// Include with base class for effects.
+#include <kwineffects.h>
+
+
+namespace KWin
+{
+
+class DimInactiveEffect
+    : public Effect
+    {
+    public:
+        DimInactiveEffect();
+        virtual void paintWindow( EffectWindow* w, int mask, QRegion region, WindowPaintData& data );
+        virtual void windowActivated( EffectWindow* c );
+    private:
+        EffectWindow* active;
+        bool dim_panels; // do/don't dim also all panels
+        bool dim_by_group; // keep visible all windows from the active window's group or only the active window
+    };
+
+} // namespace
+
+#endif
diff --git a/group.cpp b/group.cpp
index 481700e8d2..0413539944 100644
--- a/group.cpp
+++ b/group.cpp
@@ -21,6 +21,7 @@ License. See the file "COPYING" for the exact licensing terms.
 
 #include "workspace.h"
 #include "client.h"
+#include "effects.h"
 
 #include <assert.h>
 #include <kstartupinfo.h>
@@ -36,164 +37,6 @@ License. See the file "COPYING" for the exact licensing terms.
 namespace KWin
 {
 
-/*
- Consistency checks for window relations. Since transients are determinated
- using Client::transiency_list and main windows are determined using Client::transientFor()
- or the group for group transients, these have to match both ways.
-*/
-//#define ENABLE_TRANSIENCY_CHECK
-
-#ifdef NDEBUG
-#undef ENABLE_TRANSIENCY_CHECK
-#endif
-
-#ifdef ENABLE_TRANSIENCY_CHECK
-static bool transiencyCheckNonExistent = false;
-
-bool performTransiencyCheck()
-    {
-    bool ret = true;
-    ClientList clients = Workspace::self()->clients;
-    for( ClientList::ConstIterator it1 = clients.begin();
-         it1 != clients.end();
-         ++it1 )
-        {
-        if( (*it1)->deleting )
-            continue;
-        if( (*it1)->in_group == NULL )
-            {
-            kdDebug() << "TC: " << *it1 << " in not in a group" << endl;
-            ret = false;
-            }
-        else if( !(*it1)->in_group->members().contains( *it1 ))
-            {
-            kdDebug() << "TC: " << *it1 << " has a group " << (*it1)->in_group << " but group does not contain it" << endl;
-            ret = false;
-            }
-        if( !(*it1)->isTransient())
-            {
-            if( !(*it1)->mainClients().isEmpty())
-                {
-                kdDebug() << "TC: " << *it1 << " is not transient, has main clients:" << (*it1)->mainClients() << endl;
-                ret = false;
-                }
-            }
-        else
-            {
-            ClientList mains = (*it1)->mainClients();
-            for( ClientList::ConstIterator it2 = mains.begin();
-                 it2 != mains.end();
-                 ++it2 )
-                {
-                if( transiencyCheckNonExistent
-                    && !Workspace::self()->clients.contains( *it2 )
-                    && !Workspace::self()->desktops.contains( *it2 ))
-                    {
-                    kDebug() << "TC:" << *it1 << " has non-existent main client " << endl;
-                    kDebug() << "TC2:" << *it2 << endl; // this may crash
-                    ret = false;
-                    continue;
-                    }
-                if( !(*it2)->transients_list.contains( *it1 ))
-                    {
-                    kdDebug() << "TC:" << *it1 << " has main client " << *it2 << " but main client does not have it as a transient" << endl;
-                    ret = false;
-                    }
-                }
-            }
-        ClientList trans = (*it1)->transients_list;
-        for( ClientList::ConstIterator it2 = trans.begin();
-             it2 != trans.end();
-             ++it2 )
-            {
-            if( transiencyCheckNonExistent
-                && !Workspace::self()->clients.contains( *it2 )
-                && !Workspace::self()->desktops.contains( *it2 ))
-                {
-                kDebug() << "TC:" << *it1 << " has non-existent transient " << endl;
-                kDebug() << "TC2:" << *it2 << endl; // this may crash
-                ret = false;
-                continue;
-                }
-            if( !(*it2)->mainClients().contains( *it1 ))
-                {
-                kdDebug() << "TC:" << *it1 << " has transient " << *it2 << " but transient does not have it as a main client" << endl;
-                ret = false;
-                }
-            }
-        }
-    GroupList groups = Workspace::self()->groups;
-    for( GroupList::ConstIterator it1 = groups.begin();
-         it1 != groups.end();
-         ++it1 )
-        {
-        ClientList members = (*it1)->members();
-        for( ClientList::ConstIterator it2 = members.begin();
-             it2 != members.end();
-             ++it2 )
-            {
-            if( (*it2)->in_group != *it1 )
-                {
-                kdDebug() << "TC: Group " << *it1 << " contains client " << *it2 << " but client is not in that group" << endl;
-                ret = false;
-                }
-            }
-        }
-    return ret;
-    }
-
-static QString transiencyCheckStartBt;
-static const Client* transiencyCheckClient;
-static int transiencyCheck = 0;
-
-static void startTransiencyCheck( const QString& bt, const Client* c, bool ne )
-    {
-    if( ++transiencyCheck == 1 )
-        {
-        transiencyCheckStartBt = bt;
-        transiencyCheckClient = c;
-        }
-    if( ne )
-        transiencyCheckNonExistent = true;
-    }
-static void checkTransiency()
-    {
-    if( --transiencyCheck == 0 )
-        {
-        if( !performTransiencyCheck())
-            {
-            kdDebug() << "BT:" << transiencyCheckStartBt << endl;
-            kdDebug() << "CLIENT:" << transiencyCheckClient << endl;
-            assert( false );
-            }
-        transiencyCheckNonExistent = false;
-        }
-    }
-class TransiencyChecker
-    {
-    public:
-        TransiencyChecker( const QString& bt, const Client*c ) { startTransiencyCheck( bt, c, false ); }
-        ~TransiencyChecker() { checkTransiency(); }
-    };
-
-void checkNonExistentClients()
-    {
-    startTransiencyCheck( kdBacktrace(), NULL, true );
-    checkTransiency();
-    }
-
-#define TRANSIENCY_CHECK( c ) TransiencyChecker transiency_checker( kdBacktrace(), c )
-
-#else
-
-#define TRANSIENCY_CHECK( c )
-
-void checkNonExistentClients()
-    {
-    }
-
-#endif
-
 //********************************************
 // Group
 //********************************************
@@ -203,8 +46,7 @@ Group::Group( Window leader_P, Workspace* workspace_P )
         leader_wid( leader_P ),
         _workspace( workspace_P ),
         leader_info( NULL ),
-        user_time( -1U ),
-        refcount( 0 )
+        user_time( -1U )
     {
     if( leader_P != None )
         {
@@ -213,12 +55,14 @@ Group::Group( Window leader_P, Workspace* workspace_P )
         leader_info = new NETWinInfo( display(), leader_P, workspace()->rootWin(),
             properties, 2 );
         }
+    effect_group = new EffectWindowGroupImpl( this );
     workspace()->addGroup( this, Allowed );
     }
 
 Group::~Group()
     {
     delete leader_info;
+    delete effect_group;
     }
 
 QPixmap Group::icon() const
@@ -249,7 +93,6 @@ QPixmap Group::miniIcon() const
 
 void Group::addMember( Client* member_P )
     {
-    TRANSIENCY_CHECK( member_P );
     _members.append( member_P );
 //    kDebug() << "GROUPADD:" << this << ":" << member_P << endl;
 //    kDebug() << kBacktrace() << endl;
@@ -257,30 +100,11 @@ void Group::addMember( Client* member_P )
 
 void Group::removeMember( Client* member_P )
     {
-    TRANSIENCY_CHECK( member_P );
 //    kDebug() << "GROUPREMOVE:" << this << ":" << member_P << endl;
 //    kDebug() << kBacktrace() << endl;
     Q_ASSERT( _members.contains( member_P ));
     _members.removeAll( member_P );
-// there are cases when automatic deleting of groups must be delayed,
-// e.g. when removing a member and doing some operation on the possibly
-// other members of the group (which would be however deleted already
-// if there were no other members)
-    if( refcount == 0 && _members.isEmpty())
-        {
-        workspace()->removeGroup( this, Allowed );
-        delete this;
-        }
-    }
-
-void Group::ref()
-    {
-    ++refcount;
-    }
-
-void Group::deref()
-    {
-    if( --refcount == 0 && _members.isEmpty())
+    if( _members.isEmpty())
         {
         workspace()->removeGroup( this, Allowed );
         delete this;
@@ -328,7 +152,6 @@ Group* Workspace::findGroup( Window leader ) const
 // group with windows with the same client leader.
 Group* Workspace::findClientLeaderGroup( const Client* c ) const
     {
-    TRANSIENCY_CHECK( c );
     Group* ret = NULL;
     for( ClientList::ConstIterator it = clients.begin();
          it != clients.end();
@@ -346,15 +169,14 @@ Group* Workspace::findClientLeaderGroup( const Client* c ) const
                 // This most probably means the app uses group transients without
                 // setting group for its windows. Merging the two groups is a bad
                 // hack, but there's no really good solution for this case.
-                ClientList old_group = (*it)->group()->members();
+                Group* old_group = (*it)->group();
                 // old_group autodeletes when being empty
-                for( int pos = 0;
-                     pos < old_group.count();
-                     ++pos )
+                for( int cnt = old_group->members().count();
+                     cnt > 0;
+                     --cnt )
                     {
-                    Client* tmp = old_group[ pos ];
-                    if( tmp != c )
-                        tmp->changeClientLeaderGroup( ret );
+                    Client* tmp = old_group->members().first();
+                    tmp->checkGroup( ret ); // change group
                     }
                 }
             }
@@ -413,7 +235,6 @@ void Workspace::updateOnAllDesktopsOfTransients( Client* c )
 // A new window has been mapped. Check if it's not a mainwindow for some already existing transient window.
 void Workspace::checkTransients( Window w )
     {
-    TRANSIENCY_CHECK( NULL );
     for( ClientList::ConstIterator it = clients.begin();
          it != clients.end();
          ++it )
@@ -421,14 +242,13 @@ void Workspace::checkTransients( Window w )
     }
 
 
-
 //****************************************
-// Client
+// Toplevel
 //****************************************
 
 // hacks for broken apps here
 // all resource classes are forced to be lowercase
-bool Client::resourceMatch( const Client* c1, const Client* c2 )
+bool Toplevel::resourceMatch( const Toplevel* c1, const Toplevel* c2 )
     {
     // xv has "xv" as resource name, and different strings starting with "XV" as resource class
     if( qstrncmp( c1->resourceClass(), "xv", 2 ) == 0 && c1->resourceName() == "xv" )
@@ -439,25 +259,20 @@ bool Client::resourceMatch( const Client* c1, const Client* c2 )
     return c1->resourceClass() == c2->resourceClass();
     }
 
+
+//****************************************
+// Client
+//****************************************
+
 bool Client::belongToSameApplication( const Client* c1, const Client* c2, bool active_hack )
     {
     bool same_app = false;
-
-    // tests that definitely mean they belong together
     if( c1 == c2 )
         same_app = true;
     else if( c1->isTransient() && c2->hasTransient( c1, true ))
         same_app = true; // c1 has c2 as mainwindow
     else if( c2->isTransient() && c1->hasTransient( c2, true ))
         same_app = true; // c2 has c1 as mainwindow
-    else if( c1->group() == c2->group())
-        same_app = true; // same group
-    else if( c1->wmClientLeader() == c2->wmClientLeader()
-        && c1->wmClientLeader() != c1->window() // if WM_CLIENT_LEADER is not set, it returns window(),
-        && c2->wmClientLeader() != c2->window()) // don't use in this test then
-        same_app = true; // same client leader
-
-    // tests that mean they most probably don't belong together
     else if( c1->pid() != c2->pid()
         || c1->wmClientMachine( false ) != c2->wmClientMachine( false ))
         ; // different processes
@@ -469,12 +284,17 @@ bool Client::belongToSameApplication( const Client* c1, const Client* c2, bool a
         ; // different apps
     else if( !sameAppWindowRoleMatch( c1, c2, active_hack ))
         ; // "different" apps
+    else if( c1->wmClientLeader() == c2->wmClientLeader()
+        && c1->wmClientLeader() != c1->window() // if WM_CLIENT_LEADER is not set, it returns window(),
+        && c2->wmClientLeader() != c2->window()) // don't use in this test then
+        same_app = true; // same client leader
+    else if( c1->group() == c2->group())
+        same_app = true; // same group
     else if( c1->pid() == 0 || c2->pid() == 0 )
         ; // old apps that don't have _NET_WM_PID, consider them different
           // if they weren't found to match above
     else
         same_app = true; // looks like it's the same app
-
     return same_app;
     }
 
@@ -579,7 +399,6 @@ bool Client::sameAppWindowRoleMatch( const Client* c1, const Client* c2, bool ac
 
 void Client::readTransient()
     {
-    TRANSIENCY_CHECK( this );
     Window new_transient_for_id;
     if( XGetTransientForHint( display(), window(), &new_transient_for_id ))
         {
@@ -596,7 +415,6 @@ void Client::readTransient()
 
 void Client::setTransient( Window new_transient_for_id )
     {
-    TRANSIENCY_CHECK( this );
     if( new_transient_for_id != transient_for_id )
         {
         removeFromMainClients();
@@ -617,7 +435,6 @@ void Client::setTransient( Window new_transient_for_id )
 
 void Client::removeFromMainClients()
     {
-    TRANSIENCY_CHECK( this );
     if( transientFor() != NULL )
         transientFor()->removeTransient( this );
     if( groupTransient())
@@ -635,7 +452,6 @@ void Client::removeFromMainClients()
 // related lists.
 void Client::cleanGrouping()
     {
-    TRANSIENCY_CHECK( this );
 //    kDebug() << "CLEANGROUPING:" << this << endl;
 //    for( ClientList::ConstIterator it = group()->members().begin();
 //         it != group()->members().end();
@@ -705,7 +521,6 @@ void Client::cleanGrouping()
 // Non-group transients not causing loops are checked in verifyTransientFor().
 void Client::checkGroupTransients()
     {
-    TRANSIENCY_CHECK( this );
     for( ClientList::ConstIterator it1 = group()->members().begin();
          it1 != group()->members().end();
          ++it1 )
@@ -835,7 +650,6 @@ Window Client::verifyTransientFor( Window new_transient_for, bool defined )
 
 void Client::addTransient( Client* cl )
     {
-    TRANSIENCY_CHECK( this );
     assert( !transients_list.contains( cl ));
 //    assert( !cl->hasTransient( this, true )); will be fixed in checkGroupTransients()
     assert( cl != this );
@@ -852,7 +666,6 @@ void Client::addTransient( Client* cl )
 
 void Client::removeTransient( Client* cl )
     {
-    TRANSIENCY_CHECK( this );
 //    kDebug() << "REMOVETRANS:" << this << ":" << cl << endl;
 //    kDebug() << kBacktrace() << endl;
     transients_list.removeAll( cl );
@@ -870,7 +683,6 @@ void Client::removeTransient( Client* cl )
 // A new window has been mapped. Check if it's not a mainwindow for this already existing window.
 void Client::checkTransient( Window w )
     {
-    TRANSIENCY_CHECK( this );
     if( original_transient_for_id != w )
         return;
     w = verifyTransientFor( w, true );
@@ -951,10 +763,7 @@ Client* Client::findModal()
 // Argument is only when some specific group needs to be set.
 void Client::checkGroup( Group* set_group, bool force )
     {
-    TRANSIENCY_CHECK( this );
     Group* old_group = in_group;
-    if( old_group != NULL )
-        old_group->ref(); // turn off automatic deleting
     if( set_group != NULL )
         {
         if( set_group != in_group )
@@ -1011,21 +820,16 @@ void Client::checkGroup( Group* set_group, bool force )
                 in_group->addMember( this );
                 }
             }
-        else // Not transient without a group, put it in its client leader group.
-            { // This might be stupid if grouping was used for e.g. taskbar grouping
-              // or minimizing together the whole group, but as long as its used
-              // only for dialogs it's better to keep windows from one app in one group.
-            Group* new_group = workspace()->findClientLeaderGroup( this );
-            if( in_group != NULL && in_group != new_group )
+        else // not transient without a group, put it in its own group
+            {
+            if( in_group != NULL && in_group->leader() != window())
                 {
                 in_group->removeMember( this );            
                 in_group = NULL;
                 }
-            if( new_group == NULL )
-                new_group = new Group( None, workspace() );
-            if( in_group != new_group )
+            if( in_group == NULL )
                 {
-                in_group = new_group;
+                in_group = new Group( None, workspace());
                 in_group->addMember( this );
                 }
             }
@@ -1042,16 +846,7 @@ void Client::checkGroup( Group* set_group, bool force )
                 ++it;
             }
         if( groupTransient())
-            {
-            // no longer transient for ones in the old group
-            if( old_group != NULL )
-                {
-                for( ClientList::ConstIterator it = old_group->members().begin();
-                     it != old_group->members().end();
-                     ++it )
-                    (*it)->removeTransient( this );
-                }
-            // and make transient for all in the new group
+            { // and make transient for all in the group
             for( ClientList::ConstIterator it = group()->members().begin();
                  it != group()->members().end();
                  ++it )
@@ -1061,6 +856,25 @@ void Client::checkGroup( Group* set_group, bool force )
                 (*it)->addTransient( this );
                 }
             }
+#if 0 // TODO
+        if( groupTransient())
+            {
+            if( workspace()->findGroup( old_group )) // if it still exists
+                { // it's no longer transient for windows in the old group
+                for( ClientList::ConstIterator it = old_group->members().begin();
+                     it != old_group->members().end();
+                     ++it )
+                    (*it)->removeTransient( this );
+                }
+            // and it's transiet for all windows in the new group (this one is the most recent
+            // in the group, so it is transient only for all previous windows)
+            // loops are checked in checkGroupTransients()
+            for( ClientList::ConstIterator it = group()->members().begin();
+                 it != group()->members().end();
+                 ++it )
+                (*it)->addTransient( this );
+            }
+#endif
         // group transient splashscreens should be transient even for windows
         // in group mapped later
         for( ClientList::ConstIterator it = group()->members().begin();
@@ -1076,25 +890,11 @@ void Client::checkGroup( Group* set_group, bool force )
             addTransient( *it );
 	    }
         }
-    if( old_group != NULL )
-        old_group->deref(); // can be now deleted if empty
     checkGroupTransients();
     checkActiveModal();
     workspace()->updateClientLayer( this );
     }
 
-// used by Workspace::findClientLeaderGroup()
-void Client::changeClientLeaderGroup( Group* gr )
-    {
-    // transientFor() != NULL are in the group of their mainwindow, so keep them there
-    if( transientFor() != NULL )
-        return;
-    // also don't change the group for window which have group set
-    if( window_group )
-        return;
-    checkGroup( gr ); // change group
-    }
-
 bool Client::check_active_modal = false;
 
 void Client::checkActiveModal()
diff --git a/group.h b/group.h
index 0ad6fa0eb9..7a29eab0d8 100644
--- a/group.h
+++ b/group.h
@@ -21,6 +21,7 @@ namespace KWin
 
 class Client;
 class Workspace;
+class EffectWindowGroupImpl;
 
 class Group
     {
@@ -41,8 +42,7 @@ class Group
         bool groupEvent( XEvent* e );
         void updateUserTime( Time time = CurrentTime );
         Time userTime() const;
-        void ref();
-        void deref();
+        EffectWindowGroupImpl* effectGroup();
     private:
         void getIcons();
         void startupIdChanged();
@@ -52,7 +52,7 @@ class Group
         Workspace* _workspace;
         NETWinInfo* leader_info;
         Time user_time;
-        int refcount;
+        EffectWindowGroupImpl* effect_group;
     };
 
 inline Window Group::leader() const
@@ -85,6 +85,12 @@ inline Time Group::userTime() const
     return user_time;
     }
 
+inline
+EffectWindowGroupImpl* Group::effectGroup()
+    {
+    return effect_group;
+    }
+
 } // namespace
 
 #endif
diff --git a/lib/kwineffects.cpp b/lib/kwineffects.cpp
index ec4e38a773..a6a31fdac5 100644
--- a/lib/kwineffects.cpp
+++ b/lib/kwineffects.cpp
@@ -469,4 +469,13 @@ bool EffectWindow::isOnDesktop( int d ) const
     }
 
 
+//****************************************
+// EffectWindowGroup
+//****************************************
+
+EffectWindowGroup::~EffectWindowGroup()
+    {
+    }
+
+
 } // namespace
diff --git a/lib/kwineffects.h b/lib/kwineffects.h
index d5b56bf466..c9a15d6402 100644
--- a/lib/kwineffects.h
+++ b/lib/kwineffects.h
@@ -32,6 +32,7 @@ namespace KWin
 
 
 class EffectWindow;
+class EffectWindowGroup;
 class Effect;
 
 typedef QPair< QString, Effect* > EffectPair;
@@ -251,6 +252,9 @@ class KWIN_EXPORT EffectWindow
 
         virtual void enablePainting( int reason ) = 0;
         virtual void disablePainting( int reason ) = 0;
+        virtual void addRepaint( const QRect& r ) = 0;
+        virtual void addRepaint( int x, int y, int w, int h ) = 0;
+        virtual void addRepaintFull() = 0;
 
         virtual bool isDeleted() const = 0;
         virtual bool isMinimized() const = 0;
@@ -270,6 +274,7 @@ class KWIN_EXPORT EffectWindow
         virtual QRect rect() const = 0;
 
         virtual QString caption() const = 0;
+        virtual const EffectWindowGroup* group() const = 0;
 
         virtual bool isDesktop() const = 0;
         virtual bool isDock() const = 0;
@@ -290,6 +295,12 @@ class KWIN_EXPORT EffectWindow
 
     };
 
+class KWIN_EXPORT EffectWindowGroup
+    {
+    public:
+        virtual ~EffectWindowGroup();
+        virtual EffectWindowList members() const = 0;
+    };
 
 extern KWIN_EXPORT EffectsHandler* effects;