class Fl_Double_Window : public Fl_Window

Provides a double-buffered window. If possible this will use the X double buffering extension (Xdbe). If not, it will draw the window data into an off-screen pixmap, and then using XCopyArea to put it in the on-screen window.

To make sure that Xdbe is being used, you should use Fl::visual(FL_DOUBLE) before calling show() on any window. This will select a visual that is double buffered, if one exists.

Fl_Double_Window::Fl_Double_Window(int W, int H, const char *l=0);
Fl_Double_Window::Fl_Double_Window(int X, int Y, int W, int H, const char *l);

Exactly the same constructors as for Fl_Window.

ulong Fl_Double_Window::pixmap() const;

Under X you can get the xid of the offscreen pixmap or back buffer. This value is zero until the first time flush() is called.