[Feat]: "OnLoad" Event Handler for Segmented Control / Radio / Checkbox /etc.

**Is your feature request related to a problem? Please describe.**
I'm filtering a table based on a Segmented Control. I'd like the table to initially be filtered according to the Default Value of the control, but it isn't.

**Describe the solution you'd like**
A new Event Handler that fires once upon object creation would solve this immediate problem, but I can also see it having other uses.
