It's kind of annoying that all of the breakpoints or selected source state is lost between debug sessions. By sessions I mean from opening to devtools window to closing it, so if open devtools window, set breakpoints, close devtools window and then open it again my breakpoints are lost & my selected source file is no longer selected.
See bug 867838. While that does not try to solve state saving across toolbar closings. But you can minimize the toolbox which will still have the same state.
Bug 882341 is about preserving breakpoints, but remembering the selected source sounds like a good idea, too.
This has been lying around in P3 land for a while but I think is both surprising and puts us in a bad light when we're compared to chrome. Can you re-triage this? Happy to attend the Minotaur meeting and chat about it.
Since bug 882341 is already about preserving breakpoint state, I think it makes sense to limit the scope of this bug to preserving the selected source only. Either that, or we could merge these into a single bug.
The new debugger now supports this.