I did 'K b' to show all the buttons (5) of Lars' previous message and then
attempted to hide each one in succession.

When I got to the text/html part, the ellipses appeared after the button,
but the text did not hide.  When I clicked the button again, new text
appeared and the old text remained.  Repeating this cycle caused multiple
entries of the same text, over and over.  Here is an example of this after
several iterations: