* modules/gui/skins2/x11/x11_window.cpp: "stay on top" support if window...

* modules/gui/skins2/x11/x11_window.cpp: "stay on top" support if window manager supports _NET_WM_STATE_STAYS_ON_TOP.

modules/gui/skins2/x11/x11_window.cpp

@@ -174,7 +174,47 @@ void X11Window::setOpacity( uint8_t value ) const
 
 void X11Window::toggleOnTop( bool onTop ) const
 {
-    // TODO
+    int i_ret, i_format;
+    unsigned long i, i_items, i_bytesafter;
+    Atom net_wm_supported, net_wm_state, net_wm_state_on_top, *p_args = NULL;
+
+    net_wm_supported = XInternAtom( XDISPLAY, "_NET_SUPPORTED", False );
+
+    i_ret = XGetWindowProperty( XDISPLAY, DefaultRootWindow( XDISPLAY ),
+                                net_wm_supported,
+                                0, 16384, False, AnyPropertyType,
+                                &net_wm_supported,
+                                &i_format, &i_items, &i_bytesafter,
+                                (unsigned char **)(intptr_t)&p_args );
+
+    if( i_ret != Success || i_items == 0 ) return; /* Not supported */
+
+    net_wm_state = XInternAtom( XDISPLAY, "_NET_WM_STATE", False );
+    net_wm_state_on_top = XInternAtom( XDISPLAY, "_NET_WM_STATE_STAYS_ON_TOP",
+                                       False );
+
+    for( i = 0; i < i_items; i++ )
+    {
+        if( p_args[i] == net_wm_state_on_top ) break;
+    }
+
+    XFree( p_args );
+    if( i == i_items ) return; /* Not supported */
+
+    /* Switch "on top" status */
+    XClientMessageEvent event;
+    memset( &event, 0, sizeof( XClientMessageEvent ) );
+
+    event.type = ClientMessage;
+    event.message_type = net_wm_state;
+    event.display = XDISPLAY;
+    event.window = m_wnd;
+    event.format = 32;
+    event.data.l[ 0 ] = onTop; /* set property */
+    event.data.l[ 1 ] = net_wm_state_on_top;
+
+    XSendEvent( XDISPLAY, DefaultRootWindow( XDISPLAY ),
+                False, SubstructureRedirectMask, (XEvent*)&event );
 }
 
 #endif