Editor bug

[SquidDev]

I notice that scrolling the editor to the right and then holding backspace causes the cursor to move into the margin on the left. Doing this after scrolling down as far as possible causes some gibberish about an "Offset" to appear. If I scroll to the bottom and remove lines using the delete key instead, phantom lines appear below the final line of code. Clicking these gets the same Offset message and removes them; alternatively, scrolling down into them crashes the editor.