A right-click on a page - at least in the browser window - gives the option to, for instance, browse to a new page. Comparing the windows version of Mozilla 0.9.3 and Navigator 4.77 shows that the right-click behaviour is very different with respect to tolerance of right-drag motions. While navigator will immediately pop up the context menu with the options for selection, mozilla will wait until the button is released before presenting the menu. This reduces the efficiency with which one can use the two browsers, as the rightClick-drag-release behaviour is more fluid and faster than right-click-click to open a new window (or activate another option in the same menu)

This behaviour has already been reported, and bug 89308 deals with it. *** This bug has been marked as a duplicate of 89308 ***

yep