Default geometry for a CAPI top-level interface

Hi,

I am saving the position of my interface using the capi:top-level-interface-save-p generic function.  It works well, though I'd like to be able to set a default geometry (typically at the center of the main screen) when no geometry has been already saved.

I tried setting :best-x / y / width / height but it seems that is really for 'forcing' the geometry ...

Is there a way to do that?


Thanks!
Cam