In Help Mode, I use the "Filtered by Qt 4.5" which provides a very convenient list of all classes. But when I use the web site of qt doc with Firefox, I can write the name of the class at the end of the adress bar, and this feature is not available in Help Mode IMHO. My suggestion would be to have a LineEdit on the top of the list of classes, and to be able to write the name of the class to get it directly (in the current tab or in a new one). Maybe a search mechanism should be implemented, to get just below this LineEdit all classes containing "drop" for example.
Best Regards.