If you are using it and notice problems, it's best to log an issue or let us know at greasemonkey-dev (and be clear that it's with this version).
Enhancements:
- Script update checking (limited!). (#1053)
We have started to build script update checking. In 0.9.12, it is never automatic in the background. You may choose to check one script (right click and choose "Find updates") or all scripts ("Check for updates" in the tool menu near the top of the Add-ons Manager). If updates are found they will then be displayed. Please use this feature and let us know if it works well, or if it breaks somehow. Once we're confident that it works, we'll turn it on by default (automatically checking in the background) in a future release. - Scripts run with the latest available version of Javascript. (#1403)
- Shared window object. (#1278)
Before 0.9.0, it was possible to set properties on the window object, and other scripts would be able to read those properties. This behavior was never supported, but as the compatibility fix that broke it is no longer necessary, it has been reverted. It is still not suggested that you leverage this quirk, it is not a fully supported feature and may break again in the future. - Right-clicking a script in the Monkey Menu works, even when no editor is configured. (#1405)
- Fix launching the editor. (#1409)
- Scripts with @match could break loading all other scripts. (#1414)
- When browsing local files, menu commands for all scripts (on all tabs) no longer display. (#1424)
- Fix GM_openInTab(). (#1428)