Is your feature request related to a problem? Please describe.

If add-ons want to provide a gesture or similar to open their config dialogs, they currently have two choices:

1. Call gui.mainFrame._popupSettingsDialog, which is a private method and could thus change signature or mechanism at any moment without breakage warning. Several (reportedly over 30) add-ons currently live on the edge by using this approach, including one of mine.
2. Replicate the internals of gui.MainFrame._popupSettingsDialog to achieve the same thing, which involves some imports and careful management of parents and exceptions.

Describe the solution you'd like

I suggest that it be renamed (and an alias established for a time), to become part of the regular public API.

Describe alternatives you've considered

A (better?) alternative might be to create a new gui function which simply takes the name of a settings dialog, finds it by entry in the list, and opens it. In other words, a simplified wrapper for gui.mainFrame._popupSettingsDialog.

Additional context

I have no idea why this, of all methods, is the only one in MainFrame that is private.
Evidently somebody really didn't want this thing getting used by add-ons. Never the less, it is.