Once you have zoomed into a certain area of the diffraction pattern, you can use "tracking" to shift the viewing area of the pattern, in order to investigate other regions of it.
In order to shift the pattern viewing area ("tracking"), make sure that your mouse cursor is located within the diffraction pattern, then press the <Shift> key on your keyboard, and keep it pressed while moving the mouse around. As an alternative, you can also keep the center mouse button (or mouse wheel) pressed while moving the mouse.
That's it! You will quickly learn that this feature is extremely handy e.g. when investigating peaks or similar.