title: How can a form send a message to its owner?
body: <p>I have written an MDI based application, in which the child forms are of different types. I have now come across a situation where I need one child form to send a message to another child form, telling it to update itself. The first child form is unaware of whether the second child form is being displayed at the moment.</p>
  
  <p>I had thought of having the first child form (form A) send a message to the main MDI form (form 0), which could then check the list of MDI child forms currently being displayed on the screen. If the desired form (form B) is being displayed, then the main form could send a second message to this form (form B).</p>
  
  <p>Unfortunately, I haven't been able to write successfully the code which would enable the first child form to signal the main form. How can a child form send a message to its owner?</p>
  
  <p>TIA,
  No'am</p>