Connecting Label As Slider Listener

In this post: the OP asks a question about creating a custom TextBox position, and one of the responses suggests setting up a custom Label to display the values, and in doing so, setting up the Label as a listener for changes in the slider values. How do you do this?? I’m trying to put a TextBox for a vertical bar slider above the slider bounds rather than smack in the middle.

I tried modifying the Label class to inherit from Slider::Listener and that didn’t work. (admittedly a real shot in the dark, I can think of a few reasons this might not work)