Sadly there's a bug in [NSMutableAttributedString readFromUrl:options:DocumentAttributes:] if you enable WebKit that causes SubEthaEdit to crash on load of certain HTML files. Were aware of this now, and will fix this with the next minor update. Very sorry for the inconvenience.
In the meantime: html-files with an <html> or <!DOCTYPE tag but no <body> trigger the crash. So in the meantime you can add a <body> tag to your documents which will also make your html more valid. Nevertheless its an crashing bug that we didn't catch, and there may be other combinations that trigger it. Again, sorry for that.
My fellow CodingMonkey Martin Ott has just made available an updated his Subversion package. Since it's a security fix, i'll recommend you get it now. :-)
If you want to stay informed just subscribe to his blog rss feed.
If you like me use SEE for developing Cocoa, there are some nice features.
First: all the Cocoa selectors are in the autocompletion. Really nice. Moreover, if you press autocomplete after a space, autocomleting will match anything in the current document that starts with the word in front of the space including the space. Really cool for "self " (shows you any selector you sent to self, have a try!
As macosxhints points out you can enter *2.2 in the font panels font size text field to resize the selected font(s) relative to their current size.
But IMHO the far more useful way to do this is by doing +2 or -4 which is also possible.