Edward Tufte:

...obviously does not work at either Adobe or Apple. One would have thought this message would appear on April 1, but no...

On launching pdf files in OSX:

"Acrobat Reader 5.0 is not currently configured to be the default application for PDF files. Would you like to make PDF files open with Acrobat Reader 5.0 rather than Acrobat Reader 5.0?"

Umm... why yes! Err, well, no! Oh heck -- I dunno...

The message comes up after responding 'Yes,' and after responding 'No.' ...but I should have expected that, shouldn't I?