How does shift->SUPER::NEW works?

Hi,

I'm having a hard time trying to properly use the constructor built by 
PerlQt Designer.

I think my problem is that I don't understand how the following line 
works:
shift->SUPER::NEW(@_[0..3]); 

What does this line do with the parameters passed to the constructor and 
how do I get them once the line was executed?

If do this:

my $arg = $_[1];
shift->SUPER::NEW(@_[0..3]);  

I get the parameter I want in the $arg variable, but I think this is not 
the best way to do it as the first line is removed every time I run 
puic.

So, any comment that guides me towards the right answer would be really 
appreciated.

Regards,
Rafael