User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:39.0) Gecko/20100101 Firefox/39.0 Build ID: 20150629114848 Steps to reproduce: I wanted to debug Add-On JavaScript by using the Browser Toolbox. For "normal" non-browser JavaScript I can activated the tracer by setting about:config -> devtools.debugger.tracer = true Actual results: The about:config -> devtools.debugger.tracer = true did not seem to affect the debugger of the browser Toolbox (no tracer button visible), nor did I find an about:config option that may enable it. Expected results: Browser toolbox should have the tracer option too; either activated by the same or another about:config option.

The tracer was removed in bug 1176981 as it is unsupported and has various unsolved issues. Nick, is there a future plan for similar functionality?

(In reply to J. Ryan Stinnett [:jryans] (use ni?) from comment #1) > The tracer was removed in bug 1176981 as it is unsupported and has various > unsolved issues. > > Nick, is there a future plan for similar functionality? Using the Debugger API's onEnterFrame and Frame.onPop hooks was much too slow. If we revisit a tracing debugger in the future, we can build on top of the trace logger, which has since been exposed on the Debugger API.