In the ViewModelEditor, when selecting a ViewModelColumn, you see this:

The FollowEnable (Follow Enable) checkbox is there to reduce the need to write a VisibleExpression in the common case in which you want your VisibleExpression to be a Negation of the ReadOnlyExpression.

Example

ReadOnlyExpression:

self.ThisShouldBeReadOnlyAndInvisible

You would then also need a VisibleExpression of:

not self.ThisShouldBeReadOnlyAndInvisible

Instead of filling the VisibleExpression, simply click the FollowEnable box behind the VisibleExpression. This will use a negated ReadOnlyExpression as the VisibleExpression automatically. You will not need to maintain 2 expressions.

(The reasoning for calling it "follow enable" rather than "follow a negated readonly" is purely space-conservative.)