Making a component appear on your screen

The DisplayHandle represent a user interface component that has yet to be realised. It can be opened up inside a window in one of two ways:

wopen :: [String] -> Component (a, DisplayHandle) -> IO (a, Window)

wopen puts a component up inside a toplevel window, the first argument contain the toplevel customisation options to put in the DisplayContext environment. Given this environment, the component returns the toplevel DisplayHandle together with an arbitrary application value.

mkDC :: [String] -> IO DC

Instead of having wopen implicitly creating a DisplayContext, mkDC creates an explicit DisplayContext for an as-yet unmapped toplevel window. Components can then be created using this environment, and finally realised on the screen with realiseDH:

realiseDH :: DC -> DisplayHandle -> IO ()

Applying realiseDH repeatedly to different DisplayHandle will replace the component displayed inside the toplevel Window.