I'm working with gtkmm + cairomm I don't know if its a bug or not. I do override the expose-event function of my window. But now anything added over my window isn't rendered except drawing area that their on_expose_event is overrided too. it's like if the window was rendering over everything. My main goal is to make a borderless window with rounded corner. And a custom skin for the widgets. I can use a custom skin with Gtk::RC rc(" myfile.gtkrc"); But my last and only problem is to make a window that doesn't render over every widget... I done that with gtk+ and cairo. But i don't exactly understand why in cairomm it doesn't work. here is what i want to do with cairomm... <a href="http://img54.imageshack.us/img54/6558/steambm1.png">http://img54.imageshack.us/img54/6558/steambm1.png</a> -----------------------------------CairoWindow.cc-------------------------------------------------- #include "cairo-window.h" #include "cairo.h" CairoWindow::CairoWindow(){     this->on_screen_changed(this->get_screen()); } CairoWindow::~CairoWindow(){} bool CairoWindow::on_expose_event(GdkEventExpose* event){   Glib::RefPtr<Gdk::Window> window = get_window();   if(window)   {     Gtk::Allocation allocation = get_allocation();     const int width = allocation.get_width();     const int height = allocation.get_height ();     Cairo::RefPtr<Cairo::Context> cr = window->create_cairo_context();          cr->set_source_rgba(0.0, 0.0, 0.0, 0.0);     cr->set_operator(Cairo::OPERATOR_SOURCE );     cr->rectangle(event-> area.x, event->area.y,             event->area.width, event->area.height);     cr->clip();           cr->save();     cr->paint();           int distance = 10;         cr->set_source_rgba( 0.27f, 0.27f, 0.27f,1);         cr->move_to(distance,0);     cr->line_to(width-distance,0);     cr->curve_to(width-distance,0, width, 0, width,distance);     cr->line_to(width,height-distance);     cr->curve_to(width,height-distance,width,height,width-distance,height);     cr->line_to(distance,height);     cr->curve_to(distance,height,0,height,0,height - distance);     cr->line_to(0,distance);     cr->curve_to(0,distance,0,0,distance,0);     cr->fill();         cr->set_source_rgba(0.35f, 0.42f, 0.31f,1);     cr->move_to(distance,0);     cr->line_to(width-distance,0);     cr->curve_to(width-distance,0, width, 0, width,distance);     cr->line_to(width, distance * 3);     cr->line_to(0, distance * 3);     cr->line_to(0, distance);     cr->curve_to(0,distance, 0, 0, distance,0);     /*cairo_curve_to(cr,0, height - 5, 0, height, 5,height);     cairo_line_to(cr,0, height);     cairo_line_to(cr,width,height);     cairo_line_to(cr,width,0);*/         /*cairo_arc(cr, width / 2, height / 2, (width < height ? width : height) / 2 - 8 , 0, 2 * 3.14 );*/     cr->fill();     cr->stroke();     cr->restore();   } } void CairoWindow::on_screen_changed( const Glib::RefPtr<Gdk::Screen>& previous_screen ){     const Glib::RefPtr<Gdk::Screen> screen = this->get_screen();     const Glib::RefPtr<Gdk::Colormap> colormap = screen->get_rgba_colormap();         if(colormap){         std::cout << "Screen support alpha channel";     }else{         std::cout << "Screen support alpha channel";     }     this->set_colormap(colormap); }; ---------------------------------------------------------------------------------------------------------- ------------------------------------------CairoWindow.h-------------------------------------------- #ifndef GTKMM_CAIRO_WINDOW_H #define GTKMM_CAIRO_WINDOW_H #include <gtkmm/window.h> #include <iostream> class CairoWindow : public Gtk::Window {     public:         CairoWindow();         virtual ~CairoWindow();     protected:         //Override default signal handler:        virtual bool on_expose_event(GdkEventExpose* event);         virtual void on_screen_changed( const Glib::RefPtr<Gdk::Screen>& previous_screen);    }; #endif // GTKMM_EXAMPLE_CLOCK_H ----------------------------------------------------------------------------------------------------------- I may be missing something but i believe this is fairly simple