Hello and welcome to the forum,
In Captivate 5 you can change this icon. For CP4 I believe someone created a widget, am looking for it later on and will be back when I find it.
You may want to visit Michael's interesting and cool site wherein I think he generously provided a free widget specific to what you maybe looking for.
Here is the link.
Thanks for the link!
I've checked out that widget. It requires AS3, and my project is in AS2. I tried saving the project in AS3, and as warned in the ensuing dialog had "unpredictable" results with my converted AS2 animations. As in seizure-inducing. Entertaining, but not useful.
So then I tried reimporting my PPTX source into a new AS3 project. Although the widget makes the TOC tab disappear (as advertised) it seems to have no other effect. Clicking it doesn't do anything, whether I place the widget over a button or not, published or not, and I've yet to discover any way to configure it to make it behave otherwise. But, full disclosure, this is the first time I've tried using a widget and I may be missing something obvious to others.
When I get time, I'll play with this some more, as I've wanted to learn more about widgets anyway. To meet my deadline, however, I just added a graphic behind the default TOC tab to draw more attention to it. Good enough for now.
It would be nice if Open / Close TOC could be made a standard interactive Action. I don't know why it isn't.