[aembleton]

If its the all white page on a new tab, you can add this to your userChrome.css

  @-moz-document url("about:newtab") {  
      body {
          background-color: #000000 !important;
      }
  }

[oynqr]

It isn't. about:blank is solid white for a single frame whenever I open it, then it turns dark gray.