How to change the frame style of the slides in the "seminar" class?

A1) Method 1:
      a) first include "usepackage{fancybox}"
      b) then use
           slideframe{shadow} or
           slideframe{double} or
           slideframe{oval} or
           slideframe{Oval}
         to change frame style or use
           slideframe{none}
         to create slides without frame
     note: put these commands in the preamble will cause all slides have 
the same frame unless you use another slideframe command to change it.
The above commands can be used within any begin{slide}...end{slide}.

  Method 2:
    a) first include "usepackage{semcolor}"
    b) then use
      slideframe{scplain} or
      slideframe{scshadow} or
      slideframe{scdouble} or
      slideframe{none}