The if function now has a variable number of operands. The side panel and the dynamic assistant insert the binary form by default. Just type one or more argument separators immediately after insterting the function and see what happens. Likewise you can delete operators by typing backspace.
The binary form is a compact notation if you don't need the else clause.
However, I prefer the cases() function from the custom functions plugin, because it is more compact.

Martin Kraska
Pre-configured portable distribution of SMath Studio: https://en.smath.info/wiki/SMath%20with%20Plugins.ashx