1)
If I use two itemstep-environments on one slide, I have to adjust the item@step counter by hand in order
to prevent the two lists from appearing parallely.
Therefore I would suggest to modify the itemstep- environment by changing the item@step counter to
\newcounter{item@step}[slide]
which resets the counter on a new slide, and
by deleting
\setcounter{item@step}{0}
in the environment definiton.
If somebody really wants the "parallel effect" he can
still achieve it by adjusting the item@step counter.
2)
Sometimes I would like to uses an itemstep environment that does NOT show the first item on the first slide. Therefore I created Itemstep:
\newenvironment{Itemstep}{%
\begin{itemstep}
\addtocounter{item@step}{1} % NOT stepcounter
}{\end{itemstep}}
Regards,
Jens