User Agent: Mozilla/5.0 (Windows NT 5.1; rv:12.0) Gecko/20100101 Firefox/12.0 Build ID: 20120420145725 Steps to reproduce: When open website such as radio online that must use windows media player plugin but it not show the windows media player plugin interface. It show and run after click other tab of web page. Actual results: The windows media player plugin is not appear and run when open the web page that require this plugin. Expected results: The windows media player plugin should be run when the web page is finished load.

Please provide steps by steps including an URL

OS : Windows XP SP3 Firefox can run windows media player normal : v. 12 Step: 1.Open web page http://www.cool93.net/radio.php when it finished load page the plugin of windows media player not show and run on this page. Although, try to refresh this page many times. 2.If have other tab when click at the other tab the windows media player plugin is show on that page and run. If no other tab when click at open a new tab the windows media player plugin is run normally same.

This problem is appear since Firefox version 13 to present version

Confirmed in FF 21b5, 23.0a1 (2013-05-01) on http://thailand.jeffersonscher.com/videotest/ The WMP plugin content is displayed only after switching tabs or minimizing the browser window.

Is this a regression?

Yes, between FF 12 - 13.

Tested with http://www.cool93.net/radio.php. This problem seems to happen in Windiows XP only. Regression window(m-c) Good: http://hg.mozilla.org/mozilla-central/rev/b506d48ef7aa Mozilla/5.0 (Windows NT 5.1; rv:13.0a1) Gecko/20120131 Firefox/13.0a1 ID:20120131133632 Bad: http://hg.mozilla.org/mozilla-central/rev/15b00ab7f22d Mozilla/5.0 (Windows NT 5.1; rv:13.0a1) Gecko/20120131 Firefox/13.0a1 ID:20120131135732 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=b506d48ef7aa&tochange=15b00ab7f22d Triggered by: 15b00ab7f22d Josh Aas — Bug 90268: Change plugin instance ownership from layout to content. r=roc r=bsmedberg

Indeed, Win XP only.

I don't have an XP VM handy, can someone that can reproduce this try, in a debug build, setting the env var NSPR_LOG_MODULES="objlc:5,Plugin:5,PluginNPP:5,PluginNPN:5" and attaching the debug output?

(In reply to Alice0775 White from comment #10) > Created attachment 745296 [details] > log It looks like the env var didn't take effect, perhaps windows cmd is confused by the quotes? Can you try: > set NSPR_LOG_MODULES=objlc:5,Plugin:5,PluginNPP:5,PluginNPN:5 You should see a bunch of lines with OBJLC in them as well as additional plugin spam

set NSPR_LOG_MODULES=objlc:5,Plugin:5,PluginNPP:5,PluginNPN:5 firefox > log2.txt 2>&1

(In reply to Alice0775 White from comment #12) > Created attachment 745367 [details] > log take2 > > set NSPR_LOG_MODULES=objlc:5,Plugin:5,PluginNPP:5,PluginNPN:5 > firefox > log2.txt 2>&1 Nothing looks to be out of order here. It's possible that the older WMP plugin expects a different event ordering for SetWindow, which would explain why switching tabs fixes it.

I'm marking this bug as WONTFIX per bug #1269807. For more information see - https://blog.mozilla.org/futurereleases/2015/10/08/npapi-plugins-in-firefox/