I can tag issues in MantisBT and feel that there would be a lot of value to adding a filter for the extension to query based on a tag.
Support for filtering by "Tags"
This sounds like an interesting idea, but that code change would be extensive. Also, how exactly would you handle a new parameter tag?
Let's say one enters 2 tags. Should only tickets be listed that include both tags or tickets that are tagged with either tag?
Pull requests are always welcome.
I've added custom fields to our MantisBT installation (1.3.1). Is it possible to include them in the table when specifying the show parameter on a wiki page?
There was a request a while back to allow searches on custom fields. see https://github.com/tessus/mwExtensionMantis/issues/8
I've never worked with custom fields thus I do not know how they work and how I could make them available (but I think I have an idea).
For now the answer to your question is no, but you can open a ticket on github. I'm travelling these days and don't have time to look into it.