GdkDisplayManager

A singleton object that offers notification when displays appear or disappear.

You can use gdk.display_manager.DisplayManager.get to obtain the gdk.display_manager.DisplayManager singleton, but that should be rarely necessary. Typically, initializing GTK opens a display that you can work with without ever accessing the gdk.display_manager.DisplayManager.

The GDK library can be built with support for multiple backends. The gdk.display_manager.DisplayManager object determines which backend is used at runtime.

In the rare case that you need to influence which of the backends is being used, you can use func@Gdk.set_allowed_backends. Note that you need to call this function before initializing GTK.

Backend-specific code

When writing backend-specific code that is supposed to work with multiple GDK backends, you have to consider both compile time and runtime. At compile time, use the GDK_WINDOWING_X11, GDK_WINDOWING_WIN32 macros, etc. to find out which backends are present in the GDK library you are building your application against. At runtime, use type-check macros like GDK_IS_X11_DISPLAY() to find out which backend is in use:

#ifdef GDK_WINDOWING_X11
  if (GDK_IS_X11_DISPLAY (display))
    {
      // make X11-specific calls here
    }
  else
#endif
#ifdef GDK_WINDOWING_MACOS
  if (GDK_IS_MACOS_DISPLAY (display))
    {
      // make Quartz-specific calls here
    }
  else
#endif
  g_error ("Unsupported GDK backend");