asReadOnly

Returns a read-only view of this mutable OptionalTooltipProperty. Typical usage :

private val mutableFooProperty by optionalTooltipProperty( initialValue )
val fooProperty = mutableFooProperty.asReadOnly()
val foo by mutableFooProperty
    private set

This give private access to the mutable property, and the mutable var, but the public only has read-only access.