… is that 99% of plugins developed for previous versions 2.x-M4 should now be able to run again, unmodified, starting with release M7, due to “additional runtime compatibility mechanisms” ! This was already announced on Ed Burnette's blog as well as in the Eclipse porting guide, but I have just checked that a plugin I'm currently developing, which stopped working in M5, is alive and kicking in M7, as promised.
But it didn't stop here ! The next trick I did was to copy every directory from 'features' and 'plugins' from my older 2.1.2 install, copy all the workspace content and import the settings. Now, all my projects and my “good old” plugins are installed inside a shiny new Eclipse. And (almost) everything is working.
In case you're interested, here's my list of plugins and some observations based on simple 5-minute functionality tests:
Spindle 0.0.37, the Tapestry plugin – close to full functionality, with some error reports in the log which seem to be related with validity checking of .jwc and .page files.
Regex tester 0.9.0, regular expressions evaluations tool – ok
Quantum 2.2.4b , managing SQL files, run SQL scripts against DB – working
Jfacedbc for RDB and data management – works fine
Clay for RDB roundtrip design – nope, because it needs GEF 2.1.X which is impossible to enable under 3.0, GEF backwards compatibility would be nice
CSS editor 0.0.3 – working, but this should not be a surprise since the plugin is only for 3.0 stream
Codesugar 0.2.1 – ok
Pydev 0.3 – Python developement environment – ok
Profiler 0.5.30 – what a great profiling tool. Working fine.
VelocityUI 1.0.2, for editing Velocity templates – ok.