Reference: postMessage

postMessage(h, m, w, l) will post the message m to the window with handle h, and passing along the wparam w and lparam l. h, m, w, and l are unsigned integers.

postMessage returns True or False, depending on what happens with the message.

Examples: postMessage(getParameter("handle", "application"), 112#16, F140#16, 0) will start the screen-saver
          postMessage(getParameter("handle", "window"), 112#16, F030#16, 0) will maximize the AlgoSim window.