[Newbies] how to bring up a modal window?

[Ralph Boland]

I need to create a modal window to which I will add a number of
additional morphs.
I did in an old project (Squeak 3.11 I think) that used classes
MorphicDialogModel and MorphicMessageBox among others and so tried to
port them to my Squeak 5.3 image.
But these didn't seem to work.

Perhaps I can track down the difficulties in getting these classes to work
but perhaps the best thing for me to do is to not use them and create
my modal morphs in the appropriate way for  Squeak 5.3.

But I don't know the right way to create a modal window using Squeak 5.3.

Can someone inform me?

Hopefully this is an easy question.

Pointing me in the direction as to what/where I should read the right
documentation
would also be very helpful.

Any help much appreciated.

Ralph Boland