Created attachment 633254 [details] [diff] [review] patch We're currently adding the about: page event listeners to every about: page, including about:newtab and possibly about:blank. We should only add them to pages that need them. We also add them twice for each document and each iframe inside those documents. I have a patch that fixes the iframe piece. Fixing the twice-per-document piece is more difficult. Marco and I were investigating that in bug 749477.
BrowserOnClick got refactored, which made the code easier to maintain and understand, but this bug still exists. It doesn't seem to be a priority to address this, so unassigning self.