X and Fluxbox :: X Window System libraries and headers not found

Hi there,i've just downloaded the latest fluxbox devel version but i can't install it.

It shows
checking for x.....no

then says the X Window System libraries and headers are not found.I did apt-get install x-window-system and installed it but why is the not found problem still there?

X headers are needed any time you compile something which uses X. It's not the same as the X system itself.
If you install applications with a package system like apt or mydsl then those headers are not needed.

Installing apps from source on DSL you will find you're missing EVERYTHING you need to compile the apps, even if you have gcc/make installed, because DSL was not built to be a development distro.
However, there's currently no official debian package for fluxbox 0.9.11, so it's either you try the myDSL extension, or go through numerous headaches finding all the headers you need (which will likely end up being more than just X headers).
Another option is to compile it on another machine and copy the files into DSL. Keep in mind, though, that there are other things needed by Fluxbox which are not available in DSL. The extension was compiled without support for xft, randr, kde, and gnome so it would run without needing extra libs included in the package.

original here.