Thanks to Gábor Szabó, we now have a regex editor in Padre. Yay! Sure it's really basic at the moment, but it's a start.
The Padre Features page says this about the regex editor: "A tool that allows the less experienced users as well to build and debug a regular expressions".
Well, if your inspiration is a tool to *teach* regex, then maybe. But in general I don't quite agree on the "less experienced users" emphasis. Regex is a minilanguage, and a featureful IDE/editor and debugger helps beginners as well as experienced users a lot. Would you say Padre is a tool for the less experienced Perl programmers? Up to a certain point, it's becoming really hard/cumbersome to debug rather long and complex regular expressions.
Personally I've only used Rx Toolkit in Komodo. Its interface is simple and not as colorful as some Windows regex editors on the market, but it does the job well. If I can cite a wishlist for Rx Toolkit, it would just be to add position indicator (line number + column + offset) in each of regex/string/matches subwindow. Being able to step regex is nice too I guess, but not essential. Usually my regexes aren't *that* long/complex.
Of course the future for Padre's regex editor is to handle Perl 6 grammars, which will be a full-fledged language in itself, so there *should* be step over/trace into/watch/etc debugger features for it.