Can't Click While Page Loading

[Ben Ruppel]

This seems like a fairly recent regression.  I'm using win32, latest 
nightly build.  I used to be able to click on a link, and before the 
next page loaded, I could middle-click or click on another link on the 
page, and mozilla would go to that link or open it in a new window.  I 
can't do this any more.  Anyone else see this?