diff --git a/client.cpp b/client.cpp
index 30b3ebdad8..c39619f1d4 100644
--- a/client.cpp
+++ b/client.cpp
@@ -225,7 +225,7 @@ void Client::destroyClient()
     deleteClient( this, Allowed );
     }
 
-void Client::updateDecoration( bool check_workspace_pos, bool force, bool delay_delete )
+void Client::updateDecoration( bool check_workspace_pos, bool force )
     {
     if( !force && (( decoration == NULL && noBorder())
                     || ( decoration != NULL && !noBorder())))
@@ -233,7 +233,7 @@ void Client::updateDecoration( bool check_workspace_pos, bool force, bool delay_
     bool do_show = false;
     ++block_geometry;
     if( force )
-        destroyDecoration( delay_delete );
+        destroyDecoration();
     if( !noBorder())
         {
         decoration = workspace()->createDecoration( bridge );
@@ -255,7 +255,7 @@ void Client::updateDecoration( bool check_workspace_pos, bool force, bool delay_
         do_show = true;
         }
     else
-        destroyDecoration( delay_delete );
+        destroyDecoration();
     if( check_workspace_pos )
         checkWorkspacePosition();
     --block_geometry;
@@ -265,21 +265,14 @@ void Client::updateDecoration( bool check_workspace_pos, bool force, bool delay_
     updateFrameStrut();
     }
 
-void Client::destroyDecoration( bool delay_delete )
+void Client::destroyDecoration()
     {
     if( decoration != NULL )
         {
-        // When selecting the noborder operation from the popup menu after clicking on the menu
-        // button, the decoration should be deleted. But after closing the popup, the flow
-        // of control is still in the decoration, and the decorations usually do
-        // "button->setDown( false )". Therefore, delay the actual deleting.
-        if( delay_delete )
-            decoration->deleteLater();
-        else
-            delete decoration;
+        delete decoration;
+        decoration = NULL;
         QPoint grav = calculateGravitation( true );
         border_left = border_right = border_top = border_bottom = 0;
-        decoration = NULL;
         setMask( QRegion()); // reset shape mask
         int save_workarea_diff_x = workarea_diff_x;
         int save_workarea_diff_y = workarea_diff_y;
@@ -395,7 +388,7 @@ void Client::setUserNoBorder( bool set )
     if( user_noborder == set )
         return;
     user_noborder = set;
-    updateDecoration( true, false, true ); // delayed deletion of decoration
+    updateDecoration( true, false );
     }
 
 bool Client::grabInput()
@@ -948,10 +941,7 @@ void Client::killWindow()
     killProcess( false );
     // always kill this client at the server
     XKillClient(qt_xdisplay(), window() );
-    // needs to be delayed, because this may be called from the client
-    // popup menu, and there may be possibly code still touching
-    // this instance after returning from killWindow()
-    QTimer::singleShot( 0, this, SLOT( destroyClient()));
+    destroyClient();
     }
 
 // send a ping to the window using _NET_WM_PING if possible
diff --git a/client.h b/client.h
index 2a765c1b48..dc970a9cdc 100644
--- a/client.h
+++ b/client.h
@@ -180,7 +180,7 @@ class Client : public QObject, public KDecorationDefines
 
         void setMask( const QRegion& r, int mode = X::Unsorted );
 
-        void updateDecoration( bool check_workspace_pos, bool force = false, bool delay_delete = false );
+        void updateDecoration( bool check_workspace_pos, bool force = false );
         void checkBorderSizes();
 
     // shape extensions
@@ -349,7 +349,7 @@ class Client : public QObject, public KDecorationDefines
 
         void embedClient( Window w );    
         void detectNoBorder();
-        void destroyDecoration( bool delay_delete = false );
+        void destroyDecoration();
         void updateFrameStrut();
 
         void rawShow(); // just shows it
diff --git a/clients/b2/b2client.cpp b/clients/b2/b2client.cpp
index 19454482c0..de926f2f5f 100644
--- a/clients/b2/b2client.cpp
+++ b/clients/b2/b2client.cpp
@@ -757,7 +757,10 @@ void B2Client::menuButtonPressed()
 {
     QPoint menupoint = button[BtnMenu]->mapToGlobal(
 	    button[BtnMenu]->rect().bottomLeft());
+    KDecorationFactory* f = factory();
     showWindowMenu(menupoint);
+    if( !f->exists( this )) // 'this' was destroyed
+        return;
     button[BtnMenu]->setDown(false);
 }
 
diff --git a/clients/default/kdedefault.cpp b/clients/default/kdedefault.cpp
index 6daff8d1b2..224f8c9f7f 100644
--- a/clients/default/kdedefault.cpp
+++ b/clients/default/kdedefault.cpp
@@ -1277,7 +1277,10 @@ void KDEDefaultClient::menuButtonPressed()
 
 	QPoint menupoint ( button[BtnMenu]->rect().bottomLeft().x()-1,
 					   button[BtnMenu]->rect().bottomLeft().y()+2 );
+        KDecorationFactory* f = factory();
 	showWindowMenu( button[BtnMenu]->mapToGlobal( menupoint ));
+        if( !f->exists( this )) // 'this' was destroyed
+            return;
 	button[BtnMenu]->setDown(false);
 }
 
diff --git a/clients/keramik/keramik.cpp b/clients/keramik/keramik.cpp
index 87e7a1d683..0faf299074 100644
--- a/clients/keramik/keramik.cpp
+++ b/clients/keramik/keramik.cpp
@@ -1314,7 +1314,10 @@ void KeramikClient::menuButtonPressed()
 {
 	QPoint menuPoint ( button[MenuButton]->rect().bottomLeft().x() - 6,
 					   button[MenuButton]->rect().bottomLeft().y() + 3 );
+        KDecorationFactory* f = factory();
 	showWindowMenu( button[MenuButton]->mapToGlobal( menuPoint ));
+        if( !f->exists( this )) // 'this' was destroyed
+            return;
 	button[MenuButton]->setDown(false);
 }
 
diff --git a/clients/quartz/quartz.cpp b/clients/quartz/quartz.cpp
index 211fcd3bcb..ec7bc4f96a 100644
--- a/clients/quartz/quartz.cpp
+++ b/clients/quartz/quartz.cpp
@@ -971,7 +971,10 @@ void QuartzClient::menuButtonPressed()
     QPoint menupoint ( button[BtnMenu]->rect().bottomLeft().x()-1,
                        button[BtnMenu]->rect().bottomLeft().y()+2 );
 	menupoint = button[BtnMenu]->mapToGlobal( menupoint );
-	showWindowMenu(menupoint);
+        KDecorationFactory* f = factory();
+        showWindowMenu(menupoint);
+        if( !f->exists( this )) // 'this' was destroyed
+            return;
 	button[BtnMenu]->setDown(false);
 }
 
diff --git a/clients/redmond/redmond.cpp b/clients/redmond/redmond.cpp
index 3af1053306..863ec815dc 100644
--- a/clients/redmond/redmond.cpp
+++ b/clients/redmond/redmond.cpp
@@ -819,7 +819,10 @@ void RedmondDeco::menuButtonPressed()
     if (!dbl) {
 		QPoint menupoint(button[BtnMenu]->rect().bottomLeft().x()-3, 
 		                 button[BtnMenu]->rect().bottomLeft().y()+4);
+                KDecorationFactory* f = factory();
 		showWindowMenu(button[BtnMenu]->mapToGlobal(menupoint));
+                if( !f->exists( this )) // 'this' was destroyed
+                    return;
 		button[BtnMenu]->setDown(false);
     } else {
 		closeWindow();
diff --git a/geometry.cpp b/geometry.cpp
index 12e01fe36c..c3c074ba8c 100644
--- a/geometry.cpp
+++ b/geometry.cpp
@@ -653,8 +653,7 @@ void Client::getWmNormalHints()
     long msize;
     if (XGetWMNormalHints(qt_xdisplay(), window(), &xSizeHint, &msize) == 0 )
         xSizeHint.flags = 0;
-    // set defined values for basesize, minsize, maxsize, aspect and resizeinc,
-    // even if they're not in flags
+    // set defined values for the fields, even if they're not in flags
 
     // basesize is just like minsize, except for minsize is not used for aspect ratios
     // keep basesize only for aspect ratios, for size increments, keep the base
@@ -696,7 +695,7 @@ void Client::getWmNormalHints()
         xSizeHint.max_aspect.x = INT_MAX;
         xSizeHint.max_aspect.y = 1;
         }
-    if( !xSizeHint.flags & PWinGravity )
+    if( ! ( xSizeHint.flags & PWinGravity ))
         xSizeHint.win_gravity = NorthWestGravity;
     if( isManaged())
         { // update to match restrictions
@@ -1288,7 +1287,7 @@ void Client::setFullScreen( bool set, bool user )
     StackingUpdatesBlocker blocker( workspace());
     workspace()->updateClientLayer( this ); // active fullscreens get different layer
     info->setState( isFullScreen() ? NET::FullScreen : 0, NET::FullScreen );
-    updateDecoration( false, false, true ); // delayed deletion of decoration
+    updateDecoration( false, false );
     if( isFullScreen())
         setGeometry( workspace()->clientArea( MaximizeFullArea, this ));
     else
diff --git a/lib/kdecoration.h b/lib/kdecoration.h
index 30e854779b..39af6e4204 100644
--- a/lib/kdecoration.h
+++ b/lib/kdecoration.h
@@ -366,9 +366,26 @@ class KDecoration
 	 */
 	QString caption() const;
 	/**
-	 * This function invokes the window operations menu.
+	 * This function invokes the window operations menu. IMPORTANT: As a result
+         * of this function, the decoration object that called it may be destroyed
+         * after the function returns. This means that the decoration object must
+         * either return immediately after calling showWindowMenu(), or it must
+         * use KDecorationFactory::exists() to check it's still valid. For example,
+         * the code handling clicks on the menu button should look similarly like this:
+         *
+         * \code
+         * KDecorationFactory* f = factory(); // needs to be saved before
+         * showWindowMenu( button[MenuButton]->mapToGlobal( menuPoint ));
+         * if( !f->exists( this )) // destroyed, return immediately
+         *     return;
+	 * button[MenuButton]->setDown(false);
+         * \endcode
 	 */
 	void showWindowMenu( QPoint pos );
+        /**
+         * This function performs the given window operation. This function may destroy
+         * the current decoration object, just like showWindowMenu().
+         */
 	void performWindowOperation( WindowOperation op );
 	/**
 	 * If the decoration is non-rectangular, this function needs to be called
@@ -571,6 +588,8 @@ class KDecoration
 	 * This function can be called by the decoration to request 
 	 * closing of the decorated window. Note that closing the window
 	 * also involves destroying the decoration.
+         * IMPORTANT: This function may destroy the current decoration object,
+         * just like showWindowMenu().
 	 */
 	void closeWindow();
 	/**
diff --git a/lib/kdecorationfactory.cpp b/lib/kdecorationfactory.cpp
index 555967443d..38cf41ba01 100644
--- a/lib/kdecorationfactory.cpp
+++ b/lib/kdecorationfactory.cpp
@@ -52,6 +52,11 @@ QValueList< KDecorationDefines::BorderSize > KDecorationFactory::borderSizes() c
     return QValueList< BorderSize >() << BorderNormal;
     }
     
+bool KDecorationFactory::exists( const KDecoration* deco ) const
+    {
+    return _decorations.contains( const_cast< KDecoration* >( deco ));
+    }
+    
 void KDecorationFactory::addDecoration( KDecoration* deco )
     {
     _decorations.append( deco );
diff --git a/lib/kdecorationfactory.h b/lib/kdecorationfactory.h
index da04c1b810..f55f3058f2 100644
--- a/lib/kdecorationfactory.h
+++ b/lib/kdecorationfactory.h
@@ -77,6 +77,13 @@ class KDecorationFactory
 	 * configuration settings for the decoration.
 	 */
         const KDecorationOptions* options(); // convenience
+        /**
+         * Returns true if the given decoration object still exists. This is necessary
+         * e.g. when calling KDecoration::showWindowMenu(), which may cause the decoration
+         * to be destroyed. Note that this function is reliable only if called immediately
+         * after such actions.
+         */
+        bool exists( const KDecoration* deco ) const;
         /**
          * @internal
          */