clicking on URLs in gnus

[jidanni@xxxxxxxxxxx]

In gnus we are reading a message when we stumble upon a URL, e.g.,
http://cpan.uwinnipeg.ca/htdocs/String-Thai-Segmentation/String/Thai/Segmentation.pm.html

Well, if we click on it, indeed there is the web page inside
emacs-w3m. But the cursor is still in the other (gnus) window, leading
to a big surprise when we hit spacebar to scroll the web page.

On the other hand, if we don't use the mouse at all, but instead hit
RET on the URL, all works as expected.

I use http://jidanni.org/comp/configuration/