That's very strange: I am using TB 10.0.2 and the UR TB extension without any problems - i received no notification about the incompatibility of this extension, and it enables me to clip TB emails perfectly (by right-clicking the mail; I don't use the TB toolbar for this).
If this doesn't work, perhaps try downloading the UR TB extension and unpacking it using a program like Total Commander. Then edit the Install.rdf file, changing the Max Version setting to 11, and save this file, after which repack it into the extension (i.e., the original .XPI file), and try reinstalling the extension in TB. (Just for the record, my Max Version setting is 9.9, but the extension still works fine.)
Alternatively, you might try "fooling" TB into accepting the current UR extension, by installing the Add On Compatibility Reporter extension -
https://addons.mozilla.org/en-us/thu...lity-reporter/. (Again, I haven't tried this, so i can't guarantee that it will work!)
Good luck - hope this helps!