The behaviour with modal dialogs seems to be to block
all input to all windows in an application. This causes
major problems with a customers help system which needs
to create new dialogs, even during a modal dialog.

>From what I can see in bugtraq this behaviour has
changed back and forth between:

 - primary application modal (only the parent frame and its
   windows affected)
 - full application modal (all windows affected)

They argue (and I think I agree with them) that it
should be the first of the two, although in 1.1.6 it is being changed
to the other. The arguments in favour are:

 - help type applications are severely crippled by full application modality 
 - the documentation seems to imply primary app. modality.      
    eg.  "modal - if true, dialog blocks input to the >>parent<< window when shown"