2.8/2.10 would nice. Since it will automatically detect it, it will make it more seamless... however, won't it make developing around a bit more difficult? Eg: program needs X functionality from 2.10 and it doesn't have it. Thus it will not work.
The biggest reason to keep the old versions available is because of windows 95/98/ME - they'll be forever stuck at gtk 2.6 and people writing stuff for them probably have very specific requirements, they won't be creating things to be used everywhere. Every Linux distro I've checked has at least 2.8, and most are on 2.10 already. Those on Windows 2000, XP, and Vista should REALLY be running 2.10 simply from the improvements in stability and features. And there's always the Gtk::get_version() to check if your app requires the newer features. Bail and give the user an error message that they really need to upgrade.
2) The GtkHTML3 and libsexy extensions
My current project depends on GtkHTML3, it would be great to see it in the full release instead of having to apply it myself. Same goes for anyone who wishes to use my program [still in heavy development, but it's coming ;-)] As well libsexy would be really useful.
I vote yes, I have them compiling on windows...gtkhtml3 even works and has fewer requirements than mozembed (believe it or not) ...we'll see what bugs pop up.
3) Installers for Win32 and OSX. I have one ready for OSX. If
Elizabeth/Steph can get around to making one for Windows in a reasonable
time-frame, we can include that in Beta.
I'm working on the installer, not sure how long it will take me to get it finished
4) Move to native Scintilla (Tom's Scintilla) instead of GtkScintilla.
This one's on me and I'll get around to it soon enough.
Works just fine on the windows end, it's all yours ;)