An Interview with Mrs. Robert Louis Stevenson, by Gelett Burgess,
in The Bookman, August, 1998:--

........

"What have you written yourself?" I asked.

"Please don't ask me that!" she exclaimed.

"But you used to paint?"

"No! But Louis once tried. I have in San Francisco a picture
he worked at with tremendous energy. It represented the arm of a
chair with a matchbox on it, and it is the funniest thing you ever
saw. He couldn't mix his oils, and finally had to use glazes and
wash the paint on like water colour. Mrs. Strong, of course, has
made innumerable sketches and caricatures at home and abroad....."

The above painting mentioned by Mrs. Robert Louis Stevenson
is in the Edwin J. Beinecke Collection.