[Inkscape-user] Can't get libpng, essential to Inkscape compile.

I installed ubuntu (actually xubuntu but that has no bearing) just to get the latest development version of Inkscape. I downloaded the source tarball, unpacked it and then went through the usual apt-get this apt-get that to get the package to configure.

The show stopper after all this was libpng, a pretty common lib. Therefore I did apt-get install libpng but ubuntu didn't recognize it. Then I copied over all the libpng files I could find on another partition to identical locations, and ran ldconfig. Now here is the current showstopper on ./configure:

png_read_info is missing.

At this point I'll do anything required, including wiping out Xubuntu and installing something else.

Anybody here know how to play this game? I sure don't.