Komodo Edit (The free version of Komodo IDE) was my previous “Text editor”, I loved it so much, because everything is extensible and also Open Source. As noted before, is based in XUL Runner, a variete of technologies, mainly XML(XUL), JavaScript, and Python, I wrote my very first python lines there.
The buffer contents, or the “editor component” are backed by scintilla.org/
In summary, is a pretty cool IDE with a lot of options for a variete of languages, and many, many features. Projects, debuggers, source-code control, and The “code Intelligence” is really smart, etc, etc. And probably everything is extensible via Mozilla add-ons community.activestate.com/addons back in time I wrote some small cool addons for older versions, such this, this, this and this. You can write anything you want on top of it, almost no limitations on extensibility.
Of course to be fair the amount of features it provides will add a little bit of slowness when compared to ST. A huge plus is that the developers are dedicated, responsive and kind to reports and criticism.
The multicursor feature is somewhat strange, or just different compared to ST. To add more cursor you first need to … right-click in the editor and choose “Select --> Multiple Selection --> Add”, then use Ctrl+Click (Cmd+Click on Mac) to quickly make additional selections.. This extra steps … I don’t know… There is a bug with multiple cursors, you can’t for example add multiple cursor and then press “SHIFT+END” which will in theory select to the end of the lines, only the first line will be selected.
If you expect from your “text editor” to be a full IDE, then Komodo IDE is great, take a look here komodoide.com/blog/2013-09/komodo-8-5-release/