Thanks vpd. That reminds me that there is also “EZ-Patch”: EZ-Patch
Now that Audacity can access Audacity’s Macro Scripting commands, it would be possible to make a plug-in that extends the selection. For example, you click on the centre of the region to be repaired, and the plug-in creates a selection that is centred on the cursor position. There is an important limitation with this: You cannot then apply a Nyquist effect to that selection in the same plug-in, it has to be run as a separate plug-in. That is, one plug-in to create the selection, and another plug-in to do the Nyquist audio processing.