old_contents: # Sample extension: zoom a window to maximum height
  
  import re
  import sys
  
  class ZoomHeight:
  
      menudefs = [
          ('windows', [
              ('_Zoom Height', '<<zoom-height>>'),
           ])
      ]
  
      windows_keydefs = {
          '<<zoom-height>>': ['<Alt-F2>'],
      }
      unix_keydefs = {
          '<<zoom-height>>': ['<Control-x><Control-z>'],
      }
  
      def __init__(self, editwin):
          self.editwin = editwin
  
      def zoom_height_event(self, event):
          top = self.editwin.top
          geom = top.wm_geometry()
          m = re.match(r"(\d+)x(\d+)\+(-?\d+)\+(-?\d+)", geom)
          if not m:
              top.bell()
              return
          width, height, x, y = map(int, m.groups())
          height = top.winfo_screenheight()
          if sys.platform == 'win32':
              y = 0
              height = height - 72
          else:
              y = 24
              height = height - 96
          newgeom = "%dx%d+%d+%d" % (width, height, x, y)
          if geom == newgeom:
              newgeom = ""
          top.wm_geometry(newgeom)
  
new_contents: # Sample extension: zoom a window to maximum height
  
  import re
  import sys
  
  class ZoomHeight:
  
      menudefs = [
          ('windows', [
              ('_Zoom Height', '<<zoom-height>>'),
           ])
      ]
  
      windows_keydefs = {
          '<<zoom-height>>': ['<Alt-F2>'],
      }
      unix_keydefs = {
          '<<zoom-height>>': ['<Control-x><Control-z>'],
      }
  
      def __init__(self, editwin):
          self.editwin = editwin
  
      def zoom_height_event(self, event):
          top = self.editwin.top
          geom = top.wm_geometry()
          m = re.match(r"(\d+)x(\d+)\+(-?\d+)\+(-?\d+)", geom)
          if not m:
              top.bell()
              return
          width, height, x, y = map(int, m.groups())
          newheight = top.winfo_screenheight()
          if sys.platform == 'win32':
              newy = 0
              newheight = newheight - 72
          else:
              newy = 24
              newheight = newheight - 96
          if height >= newheight:
              newgeom = ""
          else:
              newgeom = "%dx%d+%d+%d" % (width, newheight, x, newy)
          top.wm_geometry(newgeom)
  
subject: Use only the height to decide whether to zoom in or out.