Curious upgrade behaviour re firefox

[hg21]

Hi,

Received an update alert today.

Using adept the first 2 items were:

firefox not installed install
firefox-3.0 not installed install

Since I use Opera, I tried to "cancel changes".

With the first firefox line the "requested install" did not change.
With firefox -3.0 "cancel changes" caused that line to disappear and a firefox-2 line to appear.

When I did "cancel changes" on this firefox-2 the original 2 lines re-appeared

.

[hg21]

From further investigation I think that, because other upgrades were
sun-java (plugin etc), the update manager thought I would need firefox to use them. It presumably doesn't believe in Opera.