Dragging the mouse while holding middle-mouse button allows you to pan around the PCB layout area. However, if you have the Via or pad tool selected, each time you click the middle mouse button on the page, it creates a via/pad at that position. The wire tool does not have this problem.
Feel free to contact me for more information.
Regards,
Dax Liniere.
Brand new interactions and interfaces. 
Easy to use and quick to get started. 
