Specify if the button list should fill its defined width.
The Fill width property can be used to render all options in a CheckBox control with Render as Button List enabled the same width.
When the Fill width property is checked, you may also want to set the Control width to 100%.
The image below shows a CheckBox control rendered as a button list and "Horizontal" Orientation. The CheckBox control's width has also been set to 100%.
When Fill width is checked, the button list expands to fill the frame.