If I remember correctly there is no command for that. Also I think windows should "always" open on the primary screen (so controlling the window location on primary screen is more important). You can calculate the location and then use that to move the window (to do this properly you would probably need knowledge from operating system: screen sizes, screen resolution, scaling, screen count... which might be possible with operating system APIs. Then you need to know the window size after it has been rendered before it being rendered).
If I remember correctly, JMP tries to open windows in same location there were closed last time (not sure where I saw that comment) which is usually a good thing. And some platforms seem to be tied to the window which they are opened from.
JSL option to return mouse location would be quite helpful for some use-cases though this will still require calculations based on the window size
-Jarmo