EZ_SetScrollbarDiscreteSpeed sets the discrete scrolling
speed of a scrollbar. The discrete scrolling speed is used when
the arrow button on the scrollbar is pressed or one of the
relevent arrow keys is pressed while the scrollbar is in focus.
The default discrete scrolling speed is 1. The interpretation of this
speed depends on the context. For internal widgets that use
scrollbars, the meaning is following: for TextWidget and ListBox,
the scrolling unit is the height of a text line; for Fancy ListBox,
TreeWidget, WorkArea, the scrolling unit is one pixel.
This function returns the current discrete scrolling speed of the