Basically I'm trying to sync mp3tag and iTunes so that if I type something in to the filter box it returns the same results.
I noticed when filtering in mp3tag it produced a different result to iTunes, the reason being it appeared in the extended tag CATALOG # which iTunes doesn't search.
Is it possible to configure mp3tag to only filter certain fields or ideally has anyone found a way to match iTunes search?
OR What's the quickest way to delete all info in a list of extended tags I don't want?
I would say: ask Apple to implement a better filter like the one in MP3tag.
As the implementations differ, I would say it is pointless to use the same syntax.
Name the field that should contain a certain information.
See the help on filters and the various described options:
So what is the quickest way to filter only within all the fields currently displayed?
The MP3Tag-filter is not limited to the tags that you decide to be displayed in the list-view or the tag-panel.
There are no "normal" tags and "extended tags". "Extended Tags" in MP3Tag only means that you can invoke a view where all tags are displayed.
So you would have to tell the filter which tags you want to look for matches:
artist HAS "Rolling Stones" AND album HAS "Rolling Stones" AND ....
There is an action where you can specify which fields you want to delete or another one with which you can set which fields your want to keep - so perhaps such an action is the quickest way to delete further information.
Did you know that you can drag&drop a list from iTunes into MP3tag? So once you have filtered a list in iTunes, you d&d it to MP3tag and there is no need to apply a filter twice i.e. once in each program.