Pan image by dragging

[lubyant]

I just wonder if labelme can achieve this. Sometimes, my images are really big so I need to zoom in and trace the shape rigorously. In such case, I need to occasionally pan image. However, the way I found in labelme to do this is by clicking the scroll bar at the bottom and the right, which is somehow inconvenient.
I found the software ArcMap has a really good implementation for this functionality and probably you can take it as a good example.