Actually, by default scrolling using the arrows is really done one pixel at a time. This behavior will be changed in the official Q3 2010 Release, which is due around mid-November.
Currently, you can change the scrolling step in code-behind like this:
.radRichTextBox.VerticalScrollBar.SmallChange = 80;
// the measuring unit is px
.radRichTextBox.VerticalScrollBar.LargeChange = 200;
SmallChange refers to the pixels that will be skipped when pressing the arrow buttons and LargeChange is used when clicking in the vertical area above or below the pointer.
You can use the static methods of Telerik.Windows.Documents.Model.Unit to convert from other measuring units to dip, if you want to set the value in other units.
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items