User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:41.0) Gecko/20100101 Firefox/41.0 Build ID: 20150929144111 Steps to reproduce: "viewsource" with cmd+U on MAC OS EL Capitan displays a fullscreen window for viewing source Actual results: The full screen is displayed with the source code, but i can not close this window with my mouse, because no button appear on the top left corner on the window, even when i approach my mouse there i need to close my viewsource window with CMD+W Expected results: i thought that the usual 3 little buttons would appear on the top left corner of the window

Hmm, this feels like a Cocoa widget bug, but I am not sure. Markus, any idea if it is?

Could be, but it's usually because the browser frontend requests a fullscreen window (possibly because it has saved the fullscreen state through XUL persists?). Forwarding to our resident full screen expert.

Ah... I cannot reproduce this with Yosemite, but I don't lean to upgrading it to El Captain... It seems to me with Firefox 41 and Yosemite, it is not possible to make the viewsource window fullscreen. Is there anything changed in El Captain which makes that window fullscreen-able as well?

OK, I think I just found steps to reproduce on Firefox 41. This probably doesn't have anything to do with 10.11. I haven't tried reproducing it on Nightly yet because Nightly opens view source in a tab. STR: 1. With Firefox 41, go to any web site. 2. Fullscreen the window. 3. Press Cmd+U. The view source window appears, transitions to native fullscreen, and gets its own space. 4. Restart Firefox. 5. Now whenever you view source, the view source window will be (non-native) full screen.

i confirm : El Capitan when i am on a page : CMD+U = fullscreen view source, without any button avalaible to close or reduce the windows (same problem with contextual menu from my mouse : "view source" ) fyi : CMD+SHIFT+F (displays full screen for common browser windows) doesn't change i can only close windows with CMD+W still the problem with firefox 41.0.2

I tried this STR on 10.10.5, and after step 3, the view source window just stays as a normal window in the fullscreen space without transition to native fullscreen, and thus I cannot reproduce this issue. I guess yes, if it automatically goes to fullscreen after restart, it could be because of xul persistence, and that should be fixed in bug 1137009 (though unfortunately it was backed out recently for some regression, and new patch is still pending for review). But it seems to me that, this window shouldn't go to fullscreen at all, because it has no fullscreen button. Do these steps also apply to other windows like bookmark manager or the page info as well on 10.11? If they do, probably it is reproducible on Nightly as well. In that case, could you help testing whether my proposing patch in bug 1137009 fix this issue? There is a try build: http://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/xquan@mozilla.com-32b3dd6073a1/try-macosx64/

>Do these steps also apply to other windows like bookmark manager yes ! > the page info ? no, it remains a "poppup" window

(In reply to Xidorn Quan [:xidorn] (UTC+10, no dst) from comment #6) > I tried this STR on 10.10.5, and after step 3, the view source window just > stays as a normal window in the fullscreen space without transition to > native fullscreen, and thus I cannot reproduce this issue. Interesting. So this bug is 10.11-only after all. > I guess yes, if it automatically goes to fullscreen after restart, it could > be because of xul persistence, and that should be fixed in bug 1137009 > (though unfortunately it was backed out recently for some regression, and > new patch is still pending for review). OK. > But it seems to me that, this window shouldn't go to fullscreen at all, > because it has no fullscreen button. I found the reason: https://developer.apple.com/library/mac/releasenotes/AppKit/RN-AppKit/#10_11FullScreen > In that case, could you help testing whether my proposing patch in bug > 1137009 fix this issue? There is a try build: > http://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/xquan@mozilla.com- > 32b3dd6073a1/try-macosx64/ I'll test that build now.

By the way, an easy way of getting out of the broken state is to execute this on the error console: Services.wm.getEnumerator("navigator:view-source").getNext().fullScreen = false

(In reply to Xidorn Quan [:xidorn] (UTC+10, no dst) from comment #6) > Do these steps also apply to other windows like bookmark manager or the page > info as well on 10.11? If they do, probably it is reproducible on Nightly as > well. In that case, could you help testing whether my proposing patch in bug > 1137009 fix this issue? There is a try build: > http://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/xquan@mozilla.com- > 32b3dd6073a1/try-macosx64/ This build fixes it for me, testing with the bookmark manager. The window is automatically full-screened when opened from a full screen browser window, but after being closed and re-opened on a regular browser window it's no longer full screen.

OK, then let it depend on that bug at least. Although I have no idea whether the window automatically entering fullscreen is a desirable behavior, I guess it's much less harmful than having a broken state anyway.

The only harmful part here really is the fact that a window gets turned from native full screen (which has a way to exit full screen) into non-native full screen (which doesn't have a built-in way to exit full screen).