Draw mode should let you pan and zoom while using the line tools.

One of the biggest frustrations while drawing is when I'm building a shape with the line tool, and I need to pan around, or zoom in to be more precise, but can't. Your view is totally locked until you finish the stroke. The scroll wheel is used to control the number of points in the stroke, so I understand why that's limited. But there's no reason why you shouldn't be able to at least use the navigation controls on the right while making lines.