What inspired this wish list request?
What is the improvement you would like to see? Add configurable sliders to easily see parameter values update as you move the slider through the x or y axis. Allow multiple sliders and configurable statistics to be generated from the two.
Why is this idea important? Hover labels are bulky and can be a nuisance to lock in place without blocking other graphs or important features. Sliding updates allow the user to navigate graphs and clearly see how the data lines up without having to zoom in substantially to grab the perfect point for a hover label. This improves effectiveness of the graphing capability and can improve visual aesthetics for sharing data with others.