Incompatibility with the Open With addon?
The Open With addon allows the user to right click on a tab to launch an external program using the tab URL as an argument. However, when triggered from a TCR tab, the URL sent to the external program is moz-extension:///sidebar/sidebar.html instead of the actual URL.
I'm not sure this is fixable or if it is a problem on the TCR side, but I thought to report it in case it is.