Under linux, everything is run from the command line interface - even GUI apps, so although KDE apps are launched graphically by the user, KDE is really running exec'ing the app as if it were being running from an xterm.

Most linux apps have a version switch so that when the switch is supplied on the command line, the app reports version and exits. This switch is often -v or --version, although applications are not always consistent. KDE ( and/or Gnome ) may well have this switch defined in a style guide, so that truely compatible apps have a defined switch.

Try kmix -v, and then kmix in an xterm...
You will notice that kmix reports the versions of it's 2 major dependancies ( KDE and Trolltech's Qt library ), which is better than the Windows equivalent (Right Click..properties) that won't report .DLL versions.

I'm not really sure how Windows gets the version of an app that is reported in that way... maybe it's in the registry (possibility for corruption leading to false versions reported), or more likely, a similar method is used, and windows calls the app through a well-defined interface.