/opt/gnome and missing CApplet library

[Steve Vertigan <vertigan bigfoot com>]

I have Mandrake 7.2 and use gnome as my primary environment.  I've
recently gotten a hankering to install some apps like
galeon/evolution/etc that need newert gnome libraries than what I have. 
I can't get the latest helix binaries as Mandrake 7.2 is explicitly
warned against so I have to compile the sources.  But as I don't want to
mess up my working environment I'm trying to install to /opt/gnome
rather than /usr - where Mandrake put the current gnome.
I've downloaded gnome-core-1.4.0 and have tried running 
$./configure --prefix=/opt/gnome
but it errors out with

checking for CApplet library... Unknown library `capplet'
configure: error: Did not find CApplet library

Anyone know what I'm doing wrong?  I can't find any reference to capplet
on the gnome site or Deja.  For every file listed under "Required base
library downloads" I have an equivalent rpm installed with a >= version
number.

Also, if I ever do get it to work how will I tell subsequent
compilations to use /opt/gnome rather than /usr - and will this be a
problem that the original compile does use libraries from /usr?

Thanks,
Steve

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