OpenSolaris 200805, Missing Header Files
I realised that the this OpenSolaris 2008.05 does not come with OS header files (eg. stdio.h, ....) and X Windows include files (eg, X11/Xlib.h, ...), probably because the LiveCD version cannot afford to put too many things in 700MB. Anyway, you need to install SUNWhea and SUNWxwinc packages using "packagemanager" CLI. BTW, I was not able to launch the "Package Manager" from the "System" -> "Administration". The GUI Package Manager screwed up my keyboard input for no obvious reason.