GdkDisplayManager

The purpose of the #GdkDisplayManager singleton object is to offer notification when displays appear or disappear or the default display changes.

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

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

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:

Backend-specific code ## {#backend-specific}

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