OK I figured this out. In order to get back to the call in progress after doing nearly anything else you need to drag the header at the top of the screen down and select the call in progress there. Then you will get the screen that controls the speaker phone and can end the call too.
Thank folks for all of the good info on this forum.
Yes. And it works. I would suggest that whenever you have an operational question, if your phone is not stock, that you explain the modifications you have made. If no comment is made it is natural to assume you are asking about the stock phone. In your case, if you had mentioned that you were using Launcher Pro in the original post, I would not have answered. 'Cuz I'm not using Launcher Pro.