WIP: Don't move the window after gtk_window_present
This resolves issue #41 (closed) AKA xfce/xfce4-panel#466 (closed) where the user can see the window being moved.
GTK docs do say of moving the window before it is shown:
Window managers are free to ignore this; most window managers ignore requests for initial window positions (instead using a user-defined placement algorithm) and honor requests after the window has already been shown.
I don't think this is actually the case however. I tested this with 3 different WMs (xfwm4, mutter, openbox) and the window opened where it was expected without the second gtk_window_move call.