Newby question: filter on file type

[nji9]

I have been trying and searching... but to no success... so I ask:

I would like to filter the results of my categorized items by "item type"

I don't mean 1 extension, but a set of respectively (imges = jpg, jpeg, tif, pcx etc.).
In the filter dialog I can choose some predefined (for example images, videos, ...),
although it seems buggy all over viewtopic.php?f=62&t=40459

But I would like to define my own sets of filtering (see "documents" = doc docx txt pdf etc.).
How can I do that?
There is an option "custom" ... but haven't found how it works.

Thanks in advance

[michel038]

if that is the primary purpose of your work, maybe you should use a keyword ?
-select all pdf files , add "documents"
-select all txt files , add "documents" etc ...

Other way, for a new feature in xnviewmp, the job is almost done in "settings, file list, custom filter ..."
What you're asking for is a customization of the first column and the ability tu use it in a filter ?

[nji9]

Using a keyword for filtering...
was an idea that came into my mind too.
But it doesn't seem a good idea,
as these are two different things: filtering - labeling.

"settings, file list, custom filter ..."
Oh, now I understand what this "custom" in the filter dialog
stands for!
Yes, I could do that there.
But only for ONE class (And without name: "custom").
Say (doc, docx, pdf, odf, odt, ...) etc. for documents.

Maybe worth a suggestion to do it better?
(Define own filters)