printHello :: IO ()
printHello = putStrLn "Hello, World!"
activateApp :: Gtk.Application -> IO ()
activateApp app = do
  w <- new Gtk.ApplicationWindow [ #application := app
                                 , #title := "Haskell Gi - Examples - Hello World"
                                 , #defaultHeight := 200
                                 , #defaultWidth := 200
                                 ]
  bbox <- new Gtk.ButtonBox [ #orientation := Gtk.OrientationHorizontal ]
  #add w bbox
  btn <- new Gtk.Button [ #label := "Hello World!"]
  on btn #clicked printHello
  on btn #clicked $ Gtk.widgetDestroy w
  #add bbox btn
  #showAll w
  return ()
main :: IO ()
main = do
  app <- new Gtk.Application [ #applicationId := "haskell-gi.examples.hello-world"
                             , #flags := [ Gio.ApplicationFlagsFlagsNone ]
                             ]
  on app #activate $ activateApp app
  Gio.applicationRun app Nothing
  return ()

santi~/haskell_exploit/Exploit/src$ stack runghc Main.hs
2019-07-28 10:02:37.957 ghc[51071:1657595] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'NSWindow drag regions should only be invalidated on the Main Thread!'
*** First throw call stack:
(
        0   CoreFoundation                      0x00007fff4aadbcfd __exceptionPreprocess + 256
        1   libobjc.A.dylib                     0x00007fff75185a17 objc_exception_throw + 48
        2   CoreFoundation                      0x00007fff4aaf585d -[NSException raise] + 9
        3   AppKit                              0x00007fff4812a7ae -[NSWindow(NSWindow_Theme) _postWindowNeedsToResetDragMarginsUnlessPostingDisabled] + 317
        4   AppKit                              0x00007fff48127bdb -[NSWindow _initContent:styleMask:backing:defer:contentView:] + 1479
        5   AppKit                              0x00007fff4812760e -[NSWindow initWithContentRect:styleMask:backing:defer:] + 45
        6   AppKit                              0x00007fff483f3f08 -[NSWindow initWithContentRect:styleMask:backing:defer:screen:] + 52
        7   libgdk-3.0.dylib                    0x00000001152aacb0 -[GdkQuartzNSWindow initWithContentRect:styleMask:backing:defer:screen:] + 64
        8   libgdk-3.0.dylib                    0x00000001152b7d1e _gdk_quartz_display_create_window_impl + 1454
        9   libgdk-3.0.dylib                    0x0000000115294008 gdk_window_new + 952
        10  libgtk-3.0.dylib                    0x000000011923b27a gtk_window_realize + 1242
        11  libgtk-3.0.dylib                    0x0000000118f384aa gtk_application_window_real_realize + 186
        12  libgobject-2.0.0.dylib              0x000000010d67d6f6 _g_closure_invoke_va + 214
        13  libgobject-2.0.0.dylib              0x000000010d6942b8 g_signal_emit_valist + 1352
        14  libgobject-2.0.0.dylib              0x000000010d694d32 g_signal_emit + 130
        15  libgtk-3.0.dylib                    0x00000001192159d3 gtk_widget_realize + 291
        16  libgtk-3.0.dylib                    0x000000011923a6c3 gtk_window_show + 211
        17  libgobject-2.0.0.dylib              0x000000010d67d4fd g_closure_invoke + 189
        18  libgobject-2.0.0.dylib              0x000000010d693624 signal_emit_unlocked_R + 1316
        19  libgobject-2.0.0.dylib              0x000000010d6946b1 g_signal_emit_valist + 2369
        20  libgobject-2.0.0.dylib              0x000000010d694d32 g_signal_emit + 130
        21  libgtk-3.0.dylib                    0x0000000119215197 gtk_widget_show + 359
        22  libHSgi-gtk-3.0.30-6QmVefkNP3Q8GQ3yTLidxY-ghc8.6.5.dylib 0x0000000116a1953c sFK6L_info + 132
)
libc++abi.dylib: terminating with uncaught exception of type NSException
Abort trap: 6