Slider Size in PtScrollContainer

I would like to change the slider size of the scrollbars contained in a
PtScrollContainer. I can adjust the size of the individual scroll bars via
the Pt_ARG_SCROLLBAR_X_HEIGHT and Pt_ARG_SCROLLBAR_Y_WIDTH resources, but
I can’t find access to a Pt_ARG_SLIDER_SIZE or equivalent. I would expect
this to be the child of some part of the widget!

The application uses a touch screen and users that have large fingers
complain about the ability to “touch” the bar easily.

Thanks,

Vince Bednarz
Nordson Corp
Amherst OH