The size of the split button, expressed in percentage, respect to the total size of the button.. Can assume a value in the range from 20 to 50.
Below you can see two split buttons, the left one having the SplitButtonSizePerc property set to 20 and the right one having the same property set to 50.
It's important to note that, while the arrow is automatically repositioned in order to gain the center of the split, the caption text is not automatically repositioned and, in the case above, needed a manual horizontal repositioning through its TextDescriptor.OffsetX property.
This property is only used when the Style property of the control has been set to STYLE_SPLIT_BUTTON.
For further details about the use of the Split Button control, see the How to use the control as a Split Button section.