Could we have a checkbox on the Filter bar: [ ] Regexp
Because I would really like to be able to turn off the regexp i.e. have the filter interpret my input as a literal string. This is because it is a PITA to have to manually escape the special chars of e.g. a pathname pasted in from elsewhere. (Tell me if I'm wrong, but there's is no Mp3tag equivalent of http://uk3.php.net/preg_quote to help). Quite a few times I have forgotten to escape just one char ended up unknowingly with wrong results that have lead to lost files. Also, currently there's no mention even in the Help that the input is not literal, so I'm not surprised that a few members of the workgroup to which I've recommended Mp3tag have reported that the filter gives unreliable results. A  Regexp on the bar would 99% solve this.
Thanks for reading!