>Sometimes, we can use:
>
>_screen.forms(x).control....
>
>but sometimes we use:
>
>_vfp.activeform.activecontrol....
>
>Generally, if fail to use thisform, thisformset, especially in
>MenuBar, the above two are very useful!!
>
>But Why VFP need two difference system Object variables??
>More crazy are the _Windows, _DOS...
>why not make into one variable with different values?
>
>Some of the system variable (prefix with _ ) can not be write
>such as _pageno
>
>Quite hard to study for all predefine system variables...
>So much but seem seldom use.

The main reason here that Foxpro has rich history and MS Fox team have to support backward compatibility, e.g. VFP3 has only _SCREEN.Forms() and VFP5 was given _VFP.Activeform...