gtk:window-minimize (window)

window -- a gtk:window widget

Asks to minimize the window. Note that you should not assume the window is definitely minimized afterward, because other entities, for example, the user or window manager, could unminimize it again, or there may not be a window manager in which case minimization is not possible.

It is permitted to call this function before showing a window, in which case the window will be minimized before it ever appears onscreen.

You can track the result of this operation via the state property.