I'm trying to create some corrective shape keys, and I am finding that it would be very handy if I could hide the currently visible parts of a mesh while, at the same time, unhiding the currently hidden parts of the mesh. Is there a way to do this? 'H' will hide everything selected, Alt-H will reveal everything hidden, and Shift-H will hide everything not selected. But I want a change in hidden status that is only based on what is and isn't hidden, not on what is or isn't selected. If I could swap what is hidden and unhidden back and forth, I could really nail these problem areas quickly. As it is, the only solution I can think of is to create vertex groups for the problem areas so that I can easily select them, and then hide/unhide parts based on selection. But this means extra steps.
EDIT: If anyone can post a script which does this in one operation, I will mark it as the accepted answer.