Enable filtered popular tags by evaluating the contents of the input line

Curerently we have more than 4365 tags: http://developer.qt.nokia.com/tags/P4365/
most of them used only once: http://developer.qt.nokia.com/tags/P1530/

On the other hand, the popular tags list is too short (ca. 25 entries) as to serve all tagging purposes.
Currently it is a list of all tags restricted only to their popularity.

If there was a filtering step before evaluating popularity, this would help a lot.

pseudocode:
when input changed (also at show time):
make a list of all tags containing input.text
order descending by usage count

thats it

This suggestion was discussed before in the QtDN forum http://developer.qt.nokia.com/forums/viewthread/2177/