> and therefore did not liked it, when frequently changes broke their setup.
Which is unfortunately an inherent problem with our legacy customization approach.
And it is clearly not something the vast majority of users want, if they left Firefox for another browser that appears to them less customizable but more stable. We have run numerous user studies about what users actually care for and they have all informed what Firefox is going to be in the future.
about:permissions was an incomplete experimental UI, but a fully functional replacement is high on our priority list. We are waiting on a new design from the UX team at the moment.
This is exactly right that X means "close" or "hide this thing" and this is what it does in this case as well: it removes the non-default setting and hides the list item.
There have been a number of user studies done by Mozilla and other browser vendors that clearly show end users only have a basic grasp of the security properties of the web. So yes, more details in main UI elements leads to confusion. It's just 2 clicks for those of us who know what a certificate is (Ctrl/Cmd-I is even faster).
You are pretty much describing the Firefox architecture. We are invoking Firefox UI code from scratchpad all the time when prototyping things. Some parts of the UI do not use standard Web APIs (e.g. XUL and XBL), as there are different opinions on how the web platform should evolve to fulfill those needs, but if you include all the experimental technologies to this web kernel, we are already there.
Mozilla has been paying the main Firebug developer for a long time to work on it, but I've never heard of an open source project that would like to be "acquired", whatever that means. If hiring all of the project's developers is what you mean, quite a few of them had high profile jobs already, so funding wasn't an issue here. As for the reasons why simply incorporating Firebug into Firefox wasn't a viable solution, see the original post.
As mentioned on the hacks post, ever since Firefox 23 the web console is actually working on the same context as the debugger, when execution is paused on a breakpoint or debugger statement. You can use all the familiar tools in there to examine the current state of the page.
Mozilla can't kill Firebug, even if they wanted, since it's a separate open source project and community. And the only people with two inspectors would be those that elected to have them both, by installing Firebug and using both tools.
In order to get to that modal message, you first have to go and enable remote debugging, which is not something normal people would do. And in general, even though we can (and already have) come up with even more mitigations for the potential threat, the sad truth is that security and usability are fundamentally a tradeoff, so you have to strike a balance at some point.
Allowing websites to interact with the Debugger API is something we would like to do, but, as you note, the security implications require much more thought to get it right.
Which is unfortunately an inherent problem with our legacy customization approach.
And it is clearly not something the vast majority of users want, if they left Firefox for another browser that appears to them less customizable but more stable. We have run numerous user studies about what users actually care for and they have all informed what Firefox is going to be in the future.