Default to predetermined text for input values

[GL513]

Developer TODO (don't remove)

• [ ] create new branch. put issue number at start of name if not a very quick fix.
• [ ] write tests. put issue number in comment
• [ ] update documentation
• [ ] merge and delete branch (don't squash because want commit history to see why I made changes)

Even thought the value is "default" on the slider, when the user clicks the bubble to input a custom value, it should default to "0" and not be blank so it doesnt have a warning, and possibly confuse users.

Screenshots If applicable, add screenshots to help explain your problem. ]

[sds100]

Yeah, something like this is a good idea

[GL513]

Also for "Intent" action's description section

[sds100]

Actually, I'm not so sure. This is currently empty because it has no custom value. So I'll make the dialog clearer that this is about changing the custom value and not the default value.