I got the source file for xvidtune and tried to compile.
But the compiler complains about undefined references

undefined reference to `XF86VidModeLockModeSwitch'
undefined reference to `XF86VidModeGetModeLine'
undefined reference to `XF86VidModeGetMonitor'
undefined reference to `XF86VidModeModModeLine'
undefined reference to `XF86VidModeLockModeSwitch'
undefined reference to `XF86VidModeSwitchMode'
undefined reference to `XF86VidModeLockModeSwitch'
undefined reference to `XF86VidModeQueryVersion'
undefined reference to `XF86VidModeQueryExtension'
undefined reference to `XF86VidModeGetSaver'
undefined reference to `XF86VidModeSetSaver'
undefined reference to `XF86VidModeGetSaver'
undefined reference to `XF86VidModeSwitchMode'
undefined reference to `XF86VidModeLockModeSwitch'

I searched for these names in all my libraries without any success.
Which library do I need and where can I get it ?

Thanks in advance

        Reiner