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15.2 Window Objects

Window objects have the following methods, among others:

`open` ()
  Override this method to open a window. Store the MacOS window-id in `self.wid` and call the `do_postopen()` method to register the window with the parent application.

`close` ()
  Override this method to do any special processing on window close. Call the `do_postclose()` method to cleanup the parent state.

`do_postresize` (width, height, macoswindowid)
  Called after the window is resized. Override if more needs to be done than calling `InvalRect`.

`do_contentclick` (local, modifiers, event)
  The user clicked in the content part of a window. The arguments are the coordinates (window-relative), the key modifiers and the raw event.

`do_update` (macoswindowid, event)
  An update event for the window was received. Redraw the window.

`do_activate` (activate, event)
  The window was activated (`activate == 1`) or deactivated (`activate == 0`). Handle things like focus highlighting, etc.