UKHeliBob:
Nothing happens.....
Does your cursor change when you hover over the little triangle in the corner ?
Yes. Here is some experimental code
line a
yabba
dabba
doo
magic roundabout
showing
my
age
Yep, it works with this. The cursor changes to a 2-headed up-down arrow when I hover on the corner marker and I can make the box shorter or longer. I'm using Firefox on Ubuntu.
...R