User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0 Build ID: 20150513181056 Steps to reproduce: 1. Open the testcase in the attachments. 2. Click the button. Actual results: The site normally prevents to (there may be race conditions to get the control back): - Closing all of its tabs. - Closing the browser (except if the process gets terminated). - Focusing the address bar. - Switching to an own tab (for example to disable JavaScript in about:config). - Opening the context menu in the document.

The testcase seems to not work here well so it must be downloaded and tested locally.

This is because the page calls window.open from a blur event and somehow the popup blocker does not block the resulting window open. I actually really don't understand why, all I know is that it's making me kick myself for not fully investigating similar techniques used in bug 1116977. I wonder if this is also programmatically kicking off beforeunloads by closing popups, which then cause blur events, which then break stuff.

It is reproducible. I am changing the component. If this component is not the right fit, please change to the appropriate one. Thanks

Triaging bugs at the moment. This one is an exact duplicate of the annoying window.open() reported within Bug 675574.