How do I flush signals and gray out a menu item?

[Jeff Bergman <jbergman dynatec com>]

    I am having two problems with an application I am writing.  One is
that when I do some time-consuming processing in a loop none of the
messages get through until it is done.  Is there some call that will
flush these signals or should?  Also, I would like to be able to gray
out menu items that don't always apply.  Is there a way to do this?

Thanks for any help.