GSWYPSYZIA3JIUZJUWV3G2J7U2CIJVSXXRC26VH4QBQJRAHAJDPAC
* line-width button
* Create a file containing a single line with a reasonable number of
characters. Move the cursor towards the end of the line. Click on
line-width icon in the top margin, slide it left and right. Watch the line
of characters wrap and unwrap in response. Text should not be selected.