I'm running TBf 115.8.1 (64-bit) on Gentoo and trying to install an extenstion (Note++) for TB. When I select the *.xpi file from the 'Add-ons Manager' after having downloaded it, I get a dialog of the following: --- Add XNote++? This extension will have permissions to: Have full, unrestricted access to Thunderbird, and your computer Malicious add-ons can steal your private information or compromise your computer. Only install this add-on if you trust the source. Learn more Cancel Add --- So I select the Add button, but nothing happens, the dialog just stays there. Even if selecting Cancel nothing will happen and it doesn't go away. Thoughts? (image attached)