I'd like to know what packages I need to apt-get, but more important is,
i'd like to know what neat commands will let me search this by myself,
so that this is the last time i ask this question...
The two ways I use are to check this link to search the contents of packages:
http://www.debian.org/distrib/packages#search_contents
Second way is to use a package named apt-file. This allows a similar kind
of archive search functionality with the apt-file command.
| #include <X11/Intrinsic.h>
Searching on Intrinsic.h it seems like you may need libxt-dev.