Q: "I use Firefox Nightly, maybe it fixed the issues that are breaking your app?"
A: "If it's using -webkit prefixed CSS, that's pretty unlikely."
There's actually been talk of non-Webkit vendors supporting the webkit prefix. Opera already does, Microsoft and Mozilla have said they need to support it in at least some cases.
"Non-WebKit browser vendors first started talking about implementing the -webkit prefix [in February of 2012] during a CSS Working Group meeting. Microsoft, Mozilla and Opera all said they felt the need to support -webkit, lest their users be relegated to an inferior browsing experience (because so many sites are using only the -webkit prefix)."
Tantek Çelik of Mozilla: "At this point we're trying to figure out which and how many webkit prefix properties to actually implement support for in Mozilla. Currently we have zero. Zero is no longer an option for us."
Florian Rivoal (Opera), Sylvain Galineau (Microsoft): "Zero is not an option for us anymore either."
I hope browser vendors only implement support for webkit- prefixes for now-standard properties (eg. box-shadow), and not for properties that only WebKit implements.
> If it's using -webkit prefixed CSS, that's pretty unlikely.
Unsupported CSS features should not affect the functionality of a web app, only its appearance. Emphasis on "should"; far too many web apps end up fundamentally broken when this happens.
I think something like web-based SVG editor is pushing browser limits too far (some folks reported it crashed Chrome for them). CSS is not "just styling" here. It has functional meaning. For example invalid z-ordering, visibility or cursors can pretty much ruin the experience.
They should at least include the non-prefix css (or other prefixes) as well for when a feature becomes available on other browsers in case they forget to update it or if they're not aware of what other browsers support.
However, it does limit feedback for any of us not using Chrome. Author is probably cool with that though as it appears and I commend them for not making us jump through hoops to try it anyways by switching user agent.
The same thing can be achieved by displaying a simple warning that lets users bypass it ("oh, I was warned it might not work in my browser, and indeed it doesn't, I will take a look in Chrome").
If it's using -webkit prefixed CSS, that's pretty unlikely.
> What if I want to look at the web console to see just what breaks in case I know what the issue is?
Anyone interested in doing that should be well aware of how to spoof a user agent.