gdk:window-move (window x y)

window -- a gdk:window object
x -- an integer for the x coordinate relative to window's parent
y -- an integer for the y coordinate relative to window's parent

Repositions a window relative to its parent window. For toplevel windows, window managers may ignore or modify the move. You should probably use the gtk:window-move function on a gtk:window widget anyway, instead of using GDK functions. For child windows, the move will reliably succeed.

If you are also planning to resize the window, use the gdk:window-move-resize function to both move and resize simultaneously, for a nicer visual effect.