How to use regular expressions in "available when"?

[JMichaelTX]

@Mark

Are regular expressions available in functions like "available when", or not?

Very often, regular expressions are available anywhere you can type in text.

From this thread:
###Places where Regular Expressions can be used

@peternlewis

In almost all cases, regex is signified explicitly, usually by a menu selection that allows "matches" as an option, or for some actions like Search Variable it is always a regex.

But there are a few cases where a text field is almost always just a "contains" or "is" test (eg Button Press), and in some of those I allow regex if the entry starts with "^".

See the above thread for more examples and discussion.