Thank you for the sample solution. Unfortunately, there is no simple way to do this that I am aware of. You are on the right track though. The outermost window of the application is required to get a Location property from. Knowing the location of the window, you can also get it's size (there's numerous properties for this, but for IE I would use the Length and Width properties). With this information, you can calculate the center of the window. From here is where the fun starts. You wouldn't want to set the DesktopLocation property of your form to this location as it will set its upper left corner to these coordinates. You'll need to get the size of the form and use half of the length and the width to calculate the offset.
I'll do some more research on this though and could probably put together a script you could use that does all the math.
I did try to assign location before I posted this question and, you are right, it placed the form in the top left corner of the web page. The problem was that the setting of the TopMost property did not work consistently, that is why I abandoned an idea of the location calculation until I could solve the TopMost problem.
We want to make sure that the form is never hidden under other windows. That is the 1st priority.
In the past when I have tried this, I have first shown my form and made sure it is TopMost. Then I activate the window that I want it on top of before Activating the form I want on top. In my experience, this combination seems to work, bt if you have a different experience, perhaps I may need to get hands-on to assist.