Fixed the label not being centered when loaded hidden until after
clicking the slider.

Fixes issues presented on hidden tab rendering.

Also adding a force re-render mechanism useful when using tabs.

- Performance
- Cleanup
- Documentation

When you drag one range pointer past the other, they 'swap' and you continue dragging the other one. However, if you did this rapidly the range would wander. This locks the values so that this wandering doesn't happen.