What steps will reproduce the problem? 1. Try to install it in FireFox 6 2. 3.

What is the expected output? What do you see instead? Installation. Failure.

What version of the product are you using? On what operating system? The one that's labelled 3.5+, which isn't really. The OS is irrelevant.

Please provide any additional information below. Looks like this thing is dead.

same issue. a real problem for us, because there is also no binary for osx which we could use instead

You can unzip the xpi, modify the install.rdf file and edit the em:maxVersion tag to something higher than 6. Then zip it all together into a zip file and rename it to .xpi.

same issue here. i tried to work around with the tipp from comment2: unzipped the file with 7z, changed the install.rdf to em:maxVersion 6.6.*, zipped the folder with 7z to a .zip-archive (with the original name) and then renamed the extension to .xpi and dropped it into FF-window. result: the addon could not be installed because the file seems to be corrumpted or sth., bummer..

Don't use 7zip to compress it. If you have any version of Windows since Me, use right click, Send To > Compressed folder instead, and then rename it. If using Linux just use the 'zip -r Pencil.xpi install.rdf, update.rdf chrome.manifest chrome' command. It worked for me. I'm using version 1.2.0 from Iceweasel, and I had to add some lines to the Window overlay to add a button from which I launch Pencil.