function widget:DrawWorld()
  if internalState == "drawUnit" then
    -- not even sure if this is a way to draw a unit, but whatevs
    gl.PushMatrix()
    -- these unitDraw_* variables should be either set in a MouseDraw or fetched by some unsynced read...
    gl.Translate(unitDraw_x, unitDraw_y, unitDraw_z)
    gl.UnitShape(selUnitDef, teamId)
    gl.PopMatrix()
  end
end

-- and somewhere I have a chili button
function widget:initialize()
  window = Chili.Window:New {
     parent = screen0,
     children = {
        Chili.Button:New {
           caption = "clicky",
           OnClick = {
             function()
               internalState = "drawUnit"
             end
           }
        }
     }
  }
end