After using speedbar for a while, I found it will change the base directory according to currently displayed buffer.
How do I disable it? I just want the speedbar do nothing while I am switching to another buffer.
I don't think this behavior is possible in plain Speedbar (After looking at variables, functions and the customization window).
However, if you check out the SrSpeedbar package, I see an option: “sr-speedbar-refresh-turn-off”. Once called, it should disable refreshing; sticking to wherever it is at.