Filters with selections

Hey there.

So, I'm working on a few filters that rely on a selection to function. They work great coming out of Photoshop, but in the stand alone, there is no default selection.

This makes it difficult to know how it's going to look when it's rendered out for the library.

The way I've gotten around it is to open the LibraryPreview image, and then use the open selection to open LibraryPreviewMask.

My question is this: We have the Default.bmp, why isn't there a DefaultMask.bmp, with a choice to use it or not?

and:

Is there a better way to ajust a filter for library output? Or did I do ok? I'll have 'real' examples of the filter in the comments, but I'd love some insite on how the rest of you do filters that need selections.

It may be that filters based on selections are rare, which seems to be the case. If that IS the case, why do more people not use them?