This code is good. However, I was executing it based on the existence of the loading of the frame where IE makes the object available when completed where Firefox and Chrome make the object available as soon as it is processed. Thus, the code was executing too fast for those two browsers. I have adjusted the code to plug the function to execute in the IFrame object onload event.
So, this results in the same situation as before. In the function, I have an alert box. That alert box is shown before the frame becomes visible. This shouldn't be. Because the IFrame onload event should only occur when the frame has completed its loading process.
loIFrame=document.getElementById('IFrameMenu')
loIFrame.onload=ResizeEnvironment(nBrowserWidth)