Although it is my favorite browser, when left in its default configuration, Firefox often mangles the size of popup windows (so that some of the content is hidden) and disables manual resizing of the offending window. To change this, type “about:config” in the Firefox address bar. Then filter the results to “dom.disable” and scroll down to “dom.disable_window_open_feature.resizable”. Click on this entry to change the value to “true.” For a video demo, visit AllBusiness.
Surfnetkids » Tech Tips » Browsers » Resizing Firefox Popup Windows
Don Hill says
This solution does not work all the time, it also depends on how the popup is coded.