Feature request: Pause / Resume button

For debugging, I have inserted some `cin.get()` lines to stop program execution at a particular point.

It would be useful to have a "Pause/Continue" button so that the graph does not scroll off all the way to the left.

Alternatively a scroll bar on the x axis to scroll through the history of the data.

Really useful tool for quickly finding memory leaks by the way.

The issue names no files, tests, or entry points. Start by locating the graph update and scrolling behavior, then determine whether completion should provide a pause/resume control, x-axis history scrolling, or both; done means the graph history remains inspectable while debugging.

Written by the indexing model from the issue text.