+Finally (or, well, first), since 1.7.3, there's the **stereo width** knob.
+At the default, 100%, it makes no change to the signal, but if you turn it
+to 0% (at the middle), the signal becomes perfect mono. Between these two,
+there's a range where the channels leak partially over into each other.
+This can be useful if you have a very hard-panned signal (say, two microphones
+that point in diametrically opposite directions), which can sound odd when
+the listener is using headphones. Going further to the left, at -100%, the
+left and right channels are exactly swapped and between -100% and 0% is again
+a reversion with partial leaking. The range between -100% and 0%
+is for convenience only, as you could achieve the same effect by swapping the
+two channels in the input mapping. Note that the entire control is grayed out
+if the signal is provably mono (ie., the same input channel is mapped to both
+left and right).
+
+