[UI] We haven't discussed Host windows yet

[Gary Chambers]

Just some points:

>1-Dialogs usually are not limited to the main window.

When opening dialogs it is of the form "aMorph openModel: myDialog". If
"aMorph" is the World then it will be "system modal" otherwise modal to the
given morph (a SystemWindow, for example).
Via the theme, for a "system modal" message dialog: "UITheme current
messageIn: World text: 'Hello' title: 'Message'". 

>2-Some applications need fixed window size.
Sending #removeCornerGrips to a window after opening will essentially make
it fixed size (halos excepted).

>Not every application needs full window decorations (maximize, minimize,
close).
There is a #removeBoxes method on System window. Individially there is just
a #removeMenuBox method. I can add some more...


Some host window support would be nice too..