What are the limits of \transpush for beamer frames transition?

Question

I was looking at the different possibilities of transitions between two frames using Beamer and I found this one named \transpush which gives the impression that the slide 1 is pushed away by the slide 2.

It is possible to define two options with this transition: the direction (in degrees) and the duration (in seconds). Using the following MWE I wandered what are the limits of this transition? For example replacing in the MWE the X by 0 or 90 is ok but if I use instead 180 to get the opposite effect of the transition yielded by the value 0, something goes "wrong". I do not get any error but the transition obtained is the same as with 0! The same goes for the values 90 and 270 or -90.

Do you have the same problems or is it my slide displayer which has trouble to display the animations? Furthermore, always with the same MWE, some misalignments between the first and the second slides appear. What am I missing here?

Finally, what should I do if I want only a part of the slide to move according to the transition (and for example if I want the title of the slide to remain fixed)?

\documentclass{beamer}

\begin{document}
\begin{frame}{Slide 1}
  \begin{block}{Title 1}
    Blah blah blah.
  \end{block}
\end{frame}

\begin{frame}{Slide 2}
\transpush[direction=X,duration=1]
\begin{block}{Title 2}
  Again blah blah blah!
\end{block}
\end{frame}
\end{document}

Answer 1

With Adobe Acrobat 9 Pro the options it presents for transitions in its internal drop down menu (Advanced->Document Processing->Transitions) correspond to multiples of 45 degrees. Indeed, the following gives a second transition sliding diagonally using the option direction=45. Also direction=180 gives me the opposite to direction=0. Seeing this may require using an Adobe viewer.

\documentclass{beamer}

\begin{document}
\begin{frame}{Slide 1}
  \begin{block}{Title 1}
    Blah blah blah.
  \end{block}
\end{frame}

\begin{frame}{Slide 2}
\transpush[direction=0,duration=1]
\begin{block}{Title 2}
  Again blah blah blah!
\end{block}
\end{frame}

\begin{frame}{Slide 3}
\transpush[direction=45,duration=1]
\begin{block}{Title 3}
  Again blah blah blah!
\end{block}
\end{frame}
\end{document}