void gdk_window_maximize ( GdkWindow* window )
Maximizes the window. If the window was already maximized, then this function does nothing.
On X11, asks the window manager to maximize
window, if the window
manager supports this operation. Not all window managers support
this, and some deliberately ignore it or don’t have a concept of
“maximized”; so you can’t rely on the maximization actually
happening. But it will happen with most standard window managers,
and GDK makes a best effort to get it to happen.
On Windows, reliably maximizes the window.