With Firebird running, send it the remote command "openurl()". That is, openurl with a null argument. Firebird will open a dialog asking what file/URL you want to load, and where (current, new window, new tab, or COMPOSER). I believe this is about 12-month old UI from Seamonkey. Previously, openurl() behavior was to load the current working directory in Firebird, which was quite handy. (ie, file:///home/user). Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6b) Gecko/20031126 Firebird/0.7+
The function that brings up this UI: OpenURLDialog(domWindow) http://lxr.mozilla.org/seamonkey/source/xpfe/components/xremote/src/XRemoteService.cpp#205
This now produces this output in the terminal: "Error: Failed to send command: 500 command not parseable" Seems to address the issue raised in the original report: it doesn't bring up obsolete UI anymore. If you want -remote openurl() to do something other than complain about invalid syntax, please feel free to file a bug for that.