Tim,
I don't know that there is. However, you can set the option
to remember the window size and then after the end user resizes it
for the first time it will open at the user defined size. This
option has always been available for HTMLhelp but RoboHelp didn't
support it until recently. Since I use an old version, I can't tell
you exactly how to set it but it would be in the Window Properties.
John