my program has a long history. Build on Sparc 1, 2 and then Ultra Sparc with Solaris 2.5 using the Sun Compiler and Debugger. I never had a problem with it. now ported to Ultra Sparc 10 and also PC. os is Solaris 10 build with Solaris Developer Studio 12.3 I never had a problem with it. but in Solaris 10 there are problems with X11 libraries. For example: XAllocColorCells is not working. That's why I am now on Solaris 8. No Problems with X11. Sadly I have for Solaris 8 no Sun / Oracle compiler and now has to use GCC. bu now I have problems with the flashing of Flotingpoint Values. I understand it this way, the Floating Point Numbers representaion is nnn dot nnn like 123.456 and never with comma. Rolf.