safe to upload to externally powered Arduino Mega?

If I leave a Mega externally powered all the time, connected to its barrel jack.... is it safe to plug the USB into my computer for uploading a new program to it? Or does this create an unsafe 5V conflict with my computer's USB port, and/or stress the voltage selection circuitry on the Mega?


The Mega switches power sources automatically. It is safe to have both connected at the same time.