The entry dom.popup_allowed_events controls the pop-up events that are allowed by the pop-up blocker. The web sites are using this information to implement events for pop-ups triggered by the users, e.g. clicking a button or the page content. By default the entry contains values of "change click dblclick mouseup reset submit touchend" which means that those events are allowed on all sites by default to make a pop-up. To block all pop-ups by default simply remove all the allowed events from the entry so that the value for it shows as blank.
In short:
- Write about:config to the url bar, enter and accept the warning message
- search for popup
- double click the dom.popup_allowed_events
- remove everything from the value field
http://kb.mozillazine.org/Dom.popup_allowed_events
Please note:
Moonchild wrote:The confirmation usually requires a reload of the page, which very often will not work for web applications.