P:(Masking) Separate hidden and unhidden masks in Settings window.

When editing, masking sometimes involves trial and error where I hide masks for various reasons; they might be superceded, or I'm otherwise not using them.

It would be very convenient to be able to create a virtual copy using only the active/visible/unhidden masks - as a cleanup measure of sorts.  This could easily be accomplished by dividing the mask section into hidden and non-hidden in the settings window so we could skip the process of copying masks not in use.

To keep it simple, only the top-level 'eyeball' of a mask should be the determinant of whether a mask is hidden/unhidden; i.e. status of sub-components should be ignored.