This appears to be deliberate. According to the changelog:
> firefox (1.5.dfsg+1.5.0.1-1ubuntu4) dapper; urgency=low
>
> * Disable (by default) the `you have chosen to open' dialogue box;
> instead, we just take the default (which is to open with the
> application from the Gnome MIME database). This behaviour is
> controlled by browser.helperApps.defaultNoAsk.openFile.
>
> [...]
>
> -- Ian Jackson <email address hidden> Thu, 23 Feb 2006 14:44:42 +0000
Why would we want to remove the choice between opening and saving like this?
This appears to be deliberate. According to the changelog:
> firefox (1.5.dfsg+ 1.5.0.1- 1ubuntu4) dapper; urgency=low helperApps. defaultNoAsk. openFile.
>
> * Disable (by default) the `you have chosen to open' dialogue box;
> instead, we just take the default (which is to open with the
> application from the Gnome MIME database). This behaviour is
> controlled by browser.
>
> [...]
>
> -- Ian Jackson <email address hidden> Thu, 23 Feb 2006 14:44:42 +0000
Why would we want to remove the choice between opening and saving like this?