I propose a simple program which pops up a window saying 'Hello World' with a button saying 'Bye' which you click and it changes the message to 'Goodbye'. if you click the button again the program exits.

Hi all, Here is the GoodBye demo for the Port library. (a portable core-functionality library). I think that it nicely shows the difference between a library with a nice convenience layer, like GIO, and a bare gui library like Port. It also shows that Port is still at a reasonably high-level from a gui perspective: writing this example with just the Win32 library for example is much more work. All the best, Daan. -------------------------------------------------------------------------------- {--------------------------------------------------------------------------------This program implements the "goodbye" demo as posted by John Meacham onthe Haskell GUI mailing list. --------------------------------------------------------------------------------}module Main whereimport Graphics.UI.Portmain = do demo -- setup gui start -- start event loop demo :: IO ()demo = do w <- createWindow registerWindow w -- register for proper shutdown when the window is closed registerWindowDismiss w (closeWindow w) -- close when the user dismisses the window registerWindowPaint w (\can upd -> fillRect upd can) -- fill the background with some color setWindowDomainSize w (Size 0 0) -- no scroll bars needed setWindowViewSize w (Size 80 40) -- guess some size as Port has no layout manager setWindowTitle w "Bye!" -- set the title bar text l <- createLabel w setLabelText l "Hello World!" lsize <- getLabelRequestSize l -- get the minimal size of the label moveResizeControl l (rectAt (Point 0 0) lsize) -- position in upperleft corner b <- createButton w setButtonText b "Bye" bsize <- getButtonRequestSize b -- get the minimal size of the button moveResizeControl b (rectAt (Point 0 (sh lsize)) bsize) -- position under the label registerButtonClick b (bye w l b) -- register event handler showWindow w -- show it all where -- called on the first click with the window, label, and button as arguments. bye w l b = do setLabelText l "Goodbye" registerButtonClick b (closeWindow w) -- overwrite the old event handler