How do you disable the 'momentum' of a map window when you pan using the centre mouse button.
I do not want the map to keep moving when I release the button after a fast pan.
Agreed! If your hand has a slight tremor to it, a tiny panning movement can "throw" you pretty far from your initial view.
Fortunately, there is a setting for this: panning gestures.
Turn it off, and you're good to go.