Currently, to control the space of all items, you would have to set the StepSpacing property of RadStepProgressBar. We could include an API for controlling the spaces between each item.

Exception occurs when clearing the ItemsSource of RadStepProgressBar at runtime. The exception message is: ''-61.0133333333333' is not a valid value for property 'Width'.'. Where the "-61.013.." value will vary based on the exact code.