On my Macbook Pro running OS X 10.6.3 I can't resize a window below the top of the dock. That is, I can't drag (resize) the lower right corner of the window below the top of the dock. However, I can resize below the top of the dock on my iMac at work (also running OS X 10.6.3). Note that I can drag the whole window such that the bottom goes below the dock.
Is there a setting to control this?