GTK for the X Window System

On UNIX, the X backend is enabled by default, so you don’t need to do anything special when compiling it, and everything should just work.

To mix low-level Xlib routines into a GTK program, see GDK X Window System interaction in the GDK manual.

X11-specific environment variables

: The X11 GDK backend can be influenced with some additional environment variables.


If set, GDK makes all X requests synchronously. This is a useful option for debugging, but it will slow down the performance considerably.


Must be set to an integer, typically 2. If set, GDK will scale all windows by the specified factor. Scaled output is meant to be used on high-dpi displays. Normally, GDK will pick up a suitable scale factor for each monitor from the display system. This environment variable allows to override that.