One would expect by default that error messages instantly show up as message boxes, but they don't. One has to specify this. One also has to specify that they show up when they happen, instead of when the program ends.
Options are configured by specifying keywords in the use line rather than a hash with attributes, and manually asking for carp and croak since the default behavior isn't what one would expect.
croak does not seem to end the program, but causes it to partially lock up (though some events work and one can manually close it).
The options are nice, but the default behavior is not what the average developer would expect without reading the documentation.