Ignore events if canvas::Window is not visible

src/Canvas/gui_mgr.cxx

@@ -345,7 +345,7 @@ bool GUIMgr::handleMouse(const osgGA::GUIEventAdapter& ea)
         static_cast<WindowUserData*>(layer->getChild(j)->getUserData())
           ->window.lock();
 
-      if( !window->isCapturingEvents() )
+      if( !window->isCapturingEvents() || !window->isVisible() )
         continue;
 
       float margin = window->isResizable() ? resize_margin_pos : 0;

src/Canvas/window.cxx

@@ -109,6 +109,12 @@ namespace canvas
     return _image.getSrcCanvas();
   }
 
+  //----------------------------------------------------------------------------
+  bool Window::isVisible() const
+  {
+    return _image.isVisible();
+  }
+
   //----------------------------------------------------------------------------
   bool Window::isResizable() const
   {

src/Canvas/window.hxx

@@ -56,6 +56,7 @@ namespace canvas
       void setCanvas(simgear::canvas::CanvasPtr canvas);
       simgear::canvas::CanvasWeakPtr getCanvas() const;
 
+      bool isVisible() const;
       bool isResizable() const;
       bool isCapturingEvents() const;