This would be nice - but there's a decent workaround.
The web interface really isn't built for in-depth analysis, so when you need to do some data analysis, just download the data from the web interface into an instance of PingPlotter running locally. This gives you all the zoom/scroll/export/screenshot tools you need, while the web server continues to collect data.
We are investigating improvements to the web interface to allow this, but there are a number of higher priority items we're hard at work on first.
Thanks for the feedback.