I don't follow what you are asking.
Control the "length" as in the verticle dimension? Which
frame in particular - the TOC frame, tool bar frame or the topic
frame?
What do you mean by "longer topics...to show up in its
entirety"? You have a long TOC topic name that you want to see or
you have a long topic name (<title>) that you want to see in
the topic frame? This to me relates to "width" of a frame rather
than "length" of a frame. Are you asking two separate questions?
Regards,
GEWB