Okay, that’s really interesting. AFAIK, there’s 3 ways USB chargers handle the data pins:
- Leave them unconnected to anything (common on the cheapest chargers);
- Short them to ground. According to spec, this should indicate a dedicated charger;
- Use resistor voltage dividers to show data lines at a specific voltage, that according to spec indicates a certain allowable charge current.
A 4th option is to have some IC send a signal over the data lines, I think recent Apple chargers do that. If the touch screen problems only occur on one or some of these types of chargers, that might indicate what the problem is? Unfortunately, I don’t have the equipment to see what my charger’s data lines are doing.
I do have a USB “charger” cord (no data lines), and using that with the wall charger seemed to make the problem worse. However, the phone still didn’t have this problem when I used that cord with a laptop USB port.