Closed Bug 1279094 Opened 5 years ago Closed 3 years ago

Private tab addon and e10s causes hung window in Firefox Nightly


(Firefox :: Extension Compatibility, defect, P4)

50 Branch
Windows 7





(Reporter: lola_j22, Unassigned)



(Whiteboard: triaged)

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; x64; rv:40.0) Gecko/20100101 Firefox/40.0
Build ID: 20160608030219

Steps to reproduce:

- Turn on e10s on the latest Firefox Nightly on Windows.
- Install Private tab preview addon from
( This addon allows you mixed use of both private and non private tabs within the same window and to convert from one to the other ).
- Create a new tab then right click the tab to make private (or Ctrl+Alt+T).
( This can optionally be done by the keystroke Ctrl+Alt+P ).
- Drag this new private tab out of the window to put it into a new window.
- Attempt to close this new window or load any link in that tab.

Actual results:

The result is a window that cannot be closed and does not respond, the only way to exit Firefox fully now is to kill the process. If Firefox is left running with the window open eventually it crashes.

Expected results:

The tab should have peeled off the window and created a new working window.
OS: Unspecified → Windows 7
Hardware: Unspecified → x86_64
tracking-e10s: --- → ?
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:50.0) Gecko/20100101 Firefox/50.0
Build ID: 20160612030220

I'm seeing the same behavior regardless if the e10s is enabled or disabled. 

When I install the Private Tab add-on (installed it from:, the private detached tab is not usable and Firefox can't be closed until the process is killed from the Windows task manager.
Component: Untriaged → Extension Compatibility
Hi there,

it looks like the latest version of this add-on has an issue (with and without e10s).  Have you seen this?  troubleshot it?
tracking-e10s: + → ---
Flags: needinfo?(infocatcher.bugs)
Priority: -- → P4
Whiteboard: triaged
Looks like I can reproduce this even without Private Tab.
Simple script for Scratchpad or something else:

var script = "data:application/javascript," + encodeURIComponent(
	"docShell.QueryInterface(Components.interfaces.nsILoadContext).usePrivateBrowsing = true;"
gBrowser.selectedBrowser.messageManager.loadFrameScript(script, true);

Will turn on "usePrivateBrowsing" for current/selected tab.
Then try to drag that tab outside from window (just repeat STR from original report).
Also for me affected only tabs with about:newtab inside.
Flags: needinfo?(infocatcher.bugs)
With Firefox 57 only WebExtensions are permitted and are, by default, e10s compatible.
Closed: 3 years ago
Resolution: --- → INCOMPLETE
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