diff --git a/kcmkwin/kwinrules/Makefile.am b/kcmkwin/kwinrules/Makefile.am
index dd68b263ad..18ac989b47 100644
--- a/kcmkwin/kwinrules/Makefile.am
+++ b/kcmkwin/kwinrules/Makefile.am
@@ -3,8 +3,8 @@ AM_CPPFLAGS = $(all_includes) -DKCMRULES
 
 kde_module_LTLIBRARIES = kcm_kwinrules.la 
 
-kcm_kwinrules_la_SOURCES = main.cpp ruleswidget.cpp ruleslist.cpp kwinsrc.cpp \
-        ruleswidgetbase.ui ruleslistbase.ui
+kcm_kwinrules_la_SOURCES = main.cpp ruleswidget.cpp ruleslist.cpp kwinsrc.cpp detectwidget.cpp \
+        ruleswidgetbase.ui ruleslistbase.ui detectwidgetbase.ui
 kcm_kwinrules_la_LDFLAGS = -module -avoid-version $(all_libraries) -no-undefined
 kcm_kwinrules_la_LIBADD = $(LIB_KDEUI)
 
diff --git a/kcmkwin/kwinrules/detectwidget.cpp b/kcmkwin/kwinrules/detectwidget.cpp
new file mode 100644
index 0000000000..b1b05b944e
--- /dev/null
+++ b/kcmkwin/kwinrules/detectwidget.cpp
@@ -0,0 +1,202 @@
+/*
+ * Copyright (c) 2004 Lubos Lunak <l.lunak@kde.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "detectwidget.h"
+
+#include <kapplication.h>
+#include <klocale.h>
+#include <kdebug.h>
+#include <kxerrorhandler.h>
+#include <kwin.h>
+#include <qlabel.h>
+
+#include <X11/Xlib.h>
+#include <X11/Xatom.h>
+#include <X11/Xutil.h>
+
+namespace KWinInternal
+{
+
+DetectWidget::DetectWidget( QWidget* parent, const char* name )
+: DetectWidgetBase( parent, name )
+    {
+    }
+
+DetectDialog::DetectDialog( QWidget* parent, const char* name )
+: KDialogBase( parent, name, true, "", Ok /*| Cancel*/ )
+, grabber( NULL )
+    {
+    widget = new DetectWidget( this );
+    setMainWidget( widget );
+    }
+
+void DetectDialog::detect( WId window )
+    {
+    if( window == 0 )
+        selectWindow();
+    else
+        readWindow( window );
+    }
+
+static QCString getStringProperty(WId w, Atom prop, char separator=0)
+    {
+    Atom type;
+    int format, status;
+    unsigned long nitems = 0;
+    unsigned long extra = 0;
+    unsigned char *data = 0;
+    QCString result = "";
+    status = XGetWindowProperty( qt_xdisplay(), w, prop, 0, 10000,
+                                 FALSE, XA_STRING, &type, &format,
+                                 &nitems, &extra, &data );
+    if ( status == Success) 
+        {
+        if (data && separator) 
+            {
+            for (int i=0; i<(int)nitems; i++)
+                if (!data[i] && i+1<(int)nitems)
+                    data[i] = separator;
+            }
+        if (data)
+            result = (const char*) data;
+        XFree(data);
+        }
+    return result;
+    }
+
+void DetectDialog::readWindow( WId w )
+    {
+    if( w == 0 )
+        {
+        emit detectionDone( false );
+        return;
+        }
+    KXErrorHandler err;
+    XClassHint hint;
+    XGetClassHint( qt_xdisplay(), w, &hint );
+    Atom wm_role = XInternAtom( qt_xdisplay(), "WM_WINDOW_ROLE", False );
+    KWin::WindowInfo info = KWin::windowInfo( w );
+    if( !info.valid())
+        {
+        emit detectionDone( false );
+        return;
+        }
+    wmclass_class = hint.res_class;
+    wmclass_name = hint.res_name;
+    role = getStringProperty( w, wm_role );
+    type = info.windowType( NET::NormalMask | NET::DesktopMask | NET::DockMask
+        | NET::ToolbarMask | NET::MenuMask | NET::DialogMask | NET::OverrideMask | NET::TopMenuMask
+        | NET::UtilityMask | NET::SplashMask );
+    title = info.name();
+    extrarole = ""; // TODO
+    machine = getStringProperty( w, XA_WM_CLIENT_MACHINE );
+    if( err.error( true ))
+        {
+        emit detectionDone( false );
+        return;
+        }
+    executeDialog();
+    }
+
+void DetectDialog::executeDialog()
+    {
+    static const char* const types[] =
+        {
+        I18N_NOOP( "Normal Window" ),
+        I18N_NOOP( "Desktop" ),
+        I18N_NOOP( "Dock (panel)" ),
+        I18N_NOOP( "Toolbar" ),
+        I18N_NOOP( "Torn Off Menu" ),
+        I18N_NOOP( "Dialog Window" ),
+        I18N_NOOP( "Override Type" ),
+        I18N_NOOP( "Standalone Menubar" ),
+        I18N_NOOP( "Utility Window" ),
+        I18N_NOOP( "Splashscreen" )
+        };
+    widget->class_label->setText( wmclass_class + " (" + wmclass_name + ' ' + wmclass_class + ")" );
+    widget->role_label->setText( role );
+    if( type == NET::Unknown )
+        widget->type_label->setText( i18n( "Unknown - will be treated as Normal Window" ));
+    else
+        widget->type_label->setText( i18n( types[ type ] ));
+    widget->title_label->setText( title );
+    widget->extrarole_label->setText( extrarole );
+    widget->machine_label->setText( machine );
+    emit detectionDone( exec() == QDialog::Accepted );
+    }
+
+void DetectDialog::selectWindow()
+    {
+    // use a dialog, so that all user input is blocked
+    // use WX11BypassWM and moving away so that it's not actually visible
+    // grab only mouse, so that keyboard can be used e.g. for switching windows
+    grabber = new QDialog( NULL, NULL, true, WX11BypassWM );
+    grabber->move( -1000, -1000 );
+    grabber->show();
+    grabber->grabMouse( crossCursor );
+    grabber->installEventFilter( this );
+    }
+
+bool DetectDialog::eventFilter( QObject* o, QEvent* e )
+    {
+    if( o != grabber )
+        return false;
+    if( e->type() != QEvent::MouseButtonRelease )
+        return false;
+    delete grabber;
+    grabber = NULL;
+    readWindow( findWindow());
+    return true;
+    }
+
+WId DetectDialog::findWindow()
+    {
+    Window root;
+    Window child;
+    uint mask;
+    int rootX, rootY, x, y;
+    Window parent = qt_xrootwin();
+    Atom wm_state = XInternAtom( qt_xdisplay(), "WM_STATE", False );
+    for( int i = 0;
+         i < 10;
+         ++i )
+        {
+        XQueryPointer( qt_xdisplay(), parent, &root, &child,
+            &rootX, &rootY, &x, &y, &mask );
+        if( child == None )
+            return 0;
+        Atom type;
+        int format;
+        unsigned long nitems, after;
+        unsigned char* prop;
+        if( XGetWindowProperty( qt_xdisplay(), child, wm_state, 0, 0, False, AnyPropertyType,
+	    &type, &format, &nitems, &after, &prop ) == Success )
+            {
+	    if( prop != NULL )
+	        XFree( prop );
+	    if( type != None )
+	        return child;
+            }
+        parent = child;
+        }
+    return 0;
+    }
+
+} // namespace
+
+#include "detectwidget.moc"
diff --git a/kcmkwin/kwinrules/detectwidget.h b/kcmkwin/kwinrules/detectwidget.h
new file mode 100644
index 0000000000..509082a52c
--- /dev/null
+++ b/kcmkwin/kwinrules/detectwidget.h
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2004 Lubos Lunak <l.lunak@kde.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+
+#ifndef __DETECTWIDGET_H__
+#define __DETECTWIDGET_H__
+
+#include "detectwidgetbase.h"
+
+#include <kdialogbase.h>
+#include <netwm_def.h>
+
+namespace KWinInternal
+{
+
+class DetectWidget
+    : public DetectWidgetBase
+    {
+    Q_OBJECT
+    public:
+        DetectWidget( QWidget* parent = NULL, const char* name = NULL );
+    };
+
+class DetectDialog
+    : public KDialogBase
+    {
+    Q_OBJECT
+    public:
+        DetectDialog( QWidget* parent = NULL, const char* name = NULL );
+        void detect( WId window );
+    signals:
+        void detectionDone( bool );
+    protected:
+        virtual bool eventFilter( QObject* o, QEvent* e );
+    private:
+        void selectWindow();
+        void readWindow( WId window );
+        void executeDialog();
+        WId findWindow();
+        QCString wmclass_class;
+        QCString wmclass_name;
+        QCString role;
+        NET::WindowType type;
+        QString title;
+        QCString extrarole;
+        QCString machine;
+        DetectWidget* widget;
+        QDialog* grabber;
+    };
+
+} // namespace
+
+#endif
diff --git a/kcmkwin/kwinrules/detectwidgetbase.ui b/kcmkwin/kwinrules/detectwidgetbase.ui
new file mode 100644
index 0000000000..c110a18f95
--- /dev/null
+++ b/kcmkwin/kwinrules/detectwidgetbase.ui
@@ -0,0 +1,156 @@
+<!DOCTYPE UI><UI version="3.3" stdsetdef="1">
+<class>KWinInternal::DetectWidgetBase</class>
+<widget class="QWidget">
+    <property name="name">
+        <cstring>Form3</cstring>
+    </property>
+    <property name="geometry">
+        <rect>
+            <x>0</x>
+            <y>0</y>
+            <width>600</width>
+            <height>480</height>
+        </rect>
+    </property>
+    <property name="caption">
+        <string>Form1</string>
+    </property>
+    <vbox>
+        <property name="name">
+            <cstring>unnamed</cstring>
+        </property>
+        <widget class="QLabel">
+            <property name="name">
+                <cstring>textLabel9</cstring>
+            </property>
+            <property name="text">
+                <string>Information about the selected window:</string>
+            </property>
+        </widget>
+        <widget class="QLayoutWidget">
+            <property name="name">
+                <cstring>layout1</cstring>
+            </property>
+            <grid>
+                <property name="name">
+                    <cstring>unnamed</cstring>
+                </property>
+                <widget class="QLabel" row="0" column="0">
+                    <property name="name">
+                        <cstring>textLabel1</cstring>
+                    </property>
+                    <property name="text">
+                        <string>Class:</string>
+                    </property>
+                </widget>
+                <widget class="QLabel" row="5" column="0">
+                    <property name="name">
+                        <cstring>textLabel13</cstring>
+                    </property>
+                    <property name="text">
+                        <string>Machine:</string>
+                    </property>
+                </widget>
+                <widget class="QLabel" row="2" column="0">
+                    <property name="name">
+                        <cstring>textLabel4</cstring>
+                    </property>
+                    <property name="text">
+                        <string>Type:</string>
+                    </property>
+                </widget>
+                <widget class="QLabel" row="4" column="0">
+                    <property name="name">
+                        <cstring>textLabel11</cstring>
+                    </property>
+                    <property name="text">
+                        <string>Extra role:</string>
+                    </property>
+                </widget>
+                <widget class="QLabel" row="3" column="1">
+                    <property name="name">
+                        <cstring>title_label</cstring>
+                    </property>
+                    <property name="text">
+                        <string></string>
+                    </property>
+                </widget>
+                <widget class="QLabel" row="0" column="1">
+                    <property name="name">
+                        <cstring>class_label</cstring>
+                    </property>
+                    <property name="text">
+                        <string></string>
+                    </property>
+                </widget>
+                <widget class="QLabel" row="4" column="1">
+                    <property name="name">
+                        <cstring>extrarole_label</cstring>
+                    </property>
+                    <property name="text">
+                        <string></string>
+                    </property>
+                </widget>
+                <widget class="QLabel" row="3" column="0">
+                    <property name="name">
+                        <cstring>textLabel8</cstring>
+                    </property>
+                    <property name="text">
+                        <string>Title:</string>
+                    </property>
+                </widget>
+                <widget class="QLabel" row="5" column="1">
+                    <property name="name">
+                        <cstring>machine_label</cstring>
+                    </property>
+                    <property name="text">
+                        <string></string>
+                    </property>
+                </widget>
+                <widget class="QLabel" row="2" column="1">
+                    <property name="name">
+                        <cstring>type_label</cstring>
+                    </property>
+                    <property name="text">
+                        <string></string>
+                    </property>
+                </widget>
+                <widget class="QLabel" row="1" column="0">
+                    <property name="name">
+                        <cstring>textLabel3</cstring>
+                    </property>
+                    <property name="text">
+                        <string>Role:</string>
+                    </property>
+                </widget>
+                <widget class="QLabel" row="1" column="1">
+                    <property name="name">
+                        <cstring>role_label</cstring>
+                    </property>
+                    <property name="text">
+                        <string></string>
+                    </property>
+                </widget>
+            </grid>
+        </widget>
+        <spacer>
+            <property name="name">
+                <cstring>spacer1</cstring>
+            </property>
+            <property name="orientation">
+                <enum>Vertical</enum>
+            </property>
+            <property name="sizeType">
+                <enum>Expanding</enum>
+            </property>
+            <property name="sizeHint">
+                <size>
+                    <width>20</width>
+                    <height>40</height>
+                </size>
+            </property>
+        </spacer>
+    </vbox>
+</widget>
+<layoutdefaults spacing="6" margin="11"/>
+</UI>
diff --git a/kcmkwin/kwinrules/ruleswidget.cpp b/kcmkwin/kwinrules/ruleswidget.cpp
index 0bfbd3f03e..a77662cf14 100644
--- a/kcmkwin/kwinrules/ruleswidget.cpp
+++ b/kcmkwin/kwinrules/ruleswidget.cpp
@@ -28,9 +28,12 @@
 #include <klocale.h>
 #include <qregexp.h>
 #include <qwhatsthis.h>
+#include <assert.h>
 
 #include "../../rules.h"
 
+#include "detectwidget.h"
+
 namespace KWinInternal
 {
 
@@ -43,6 +46,7 @@ namespace KWinInternal
 
 RulesWidget::RulesWidget( QWidget* parent, const char* name )
 : RulesWidgetBase( parent, name )
+, detect_dlg( NULL )
     {
     QString enableDesc =
         i18n( "Enable this checkbox to alter this window property for the specified window(s)." );
@@ -459,6 +463,20 @@ Rules* RulesWidget::rules() const
 #undef LINEEDIT_FORCE_RULE
 #undef COMBOBOX_FORCE_RULE
 
+void RulesWidget::detectClicked()
+    {
+    assert( detect_dlg == NULL );
+    detect_dlg = new DetectDialog;
+    connect( detect_dlg, SIGNAL( detectionDone( bool )), this, SLOT( detected( bool )));
+    detect_dlg->detect( 0 );
+    }
+
+void RulesWidget::detected( bool ok )
+    {
+    delete detect_dlg;
+    detect_dlg = NULL;
+    }
+
 RulesDialog::RulesDialog( QWidget* parent, const char* name )
 : KDialogBase( parent, name, true, "", Ok | Cancel )
     {
diff --git a/kcmkwin/kwinrules/ruleswidget.h b/kcmkwin/kwinrules/ruleswidget.h
index 10e36e9310..507a1872a8 100644
--- a/kcmkwin/kwinrules/ruleswidget.h
+++ b/kcmkwin/kwinrules/ruleswidget.h
@@ -28,6 +28,7 @@ namespace KWinInternal
 {
 
 class Rules;
+class DetectDialog;
 
 class RulesWidget
     : public RulesWidgetBase
@@ -39,6 +40,8 @@ class RulesWidget
         Rules* rules() const;
     signals:
         void changed( bool state );
+    protected slots:
+        virtual void detectClicked();
     private slots:
         // geometry tab
         void updateEnableposition();
@@ -65,6 +68,10 @@ class RulesWidget
         void updateEnableignoreposition();
         void updateEnableminsize();
         void updateEnablemaxsize();
+        // internal
+        void detected( bool );
+    private:
+        DetectDialog* detect_dlg;
     };
 
 class RulesDialog
diff --git a/kcmkwin/kwinrules/ruleswidgetbase.ui b/kcmkwin/kwinrules/ruleswidgetbase.ui
index 51ec528dee..d27025f2c9 100644
--- a/kcmkwin/kwinrules/ruleswidgetbase.ui
+++ b/kcmkwin/kwinrules/ruleswidgetbase.ui
@@ -12,6 +12,9 @@
             <height>477</height>
         </rect>
     </property>
+    <property name="caption">
+        <string>Form1</string>
+    </property>
     <vbox>
         <property name="name">
             <cstring>unnamed</cstring>
@@ -275,7 +278,10 @@
                                                     <cstring>detect1</cstring>
                                                 </property>
                                                 <property name="text">
-                                                    <string>Detect (bad luck, this one doesn't work yet)</string>
+                                                    <string>&amp;Detect</string>
+                                                </property>
+                                                <property name="accel">
+                                                    <string>Alt+D</string>
                                                 </property>
                                             </widget>
                                             <spacer>
@@ -2125,6 +2131,12 @@
         <receiver>edit_reg_wmclass</receiver>
         <slot>setEnabled(bool)</slot>
     </connection>
+    <connection>
+        <sender>detect1</sender>
+        <signal>clicked()</signal>
+        <receiver>Form2</receiver>
+        <slot>detectClicked()</slot>
+    </connection>
 </connections>
 <tabstops>
     <tabstop>tabWidget2</tabstop>
@@ -2213,6 +2225,9 @@
     <tabstop>rule_maxsize</tabstop>
     <tabstop>maxsize</tabstop>
 </tabstops>
+<slots>
+    <slot access="protected">detectClicked()</slot>
+</slots>
 <layoutdefaults spacing="6" margin="11"/>
 <layoutfunctions spacing="KDialog::spacingHint" margin="KDialog::marginHint"/>
 <includehints>