Conditional hiding map windows

Various GTS modules have a ‘scenario cards’ window with separate tabs/map windows for each division. Only some of these are needed in each scenario, so the module hides unused ones on a per-scenario basis.

Does anyone know how this is accomplished? If it’s not custom code, it would handy for a project of mine. I can permanently hide something (short of editing the module), but not this per-game bit.

I kind of have a feeling it’s custom code; I remember seeing a page of checkboxes to say which of those tabs show, and I’m not finding that any more, which has me wondering if it’s custom code that has stopped working in Vassal 3.5.