Every once in a while when editing a formula, I want to add a parenthesis at the beginning of the line by pressing Shift9 to get (. However, I will accidentally press Shift8 instead, which stands for *, and the whole line gets converted to some weird rich text with a small solid red square at the beginning of the line.
I don't know what that is for, but I never want to do it and I want to disable whatever is going on; it effectively means I have to delete the line and start again because I don't know how to undo it. In fact it's happened for a long time and I've only just figured out what was actually happening. I tried looking at keyboard shortcuts online but didn't find anything for Shift8. Note that this only happens at the beginning of the line.
How can I disable this keyboard shortcut?
