It would be very useful to have a read-only toggle at the bottom of the editor window, next to the insert status display,
that could be applied to selected individual files opened in the editor.

This would prevent the programmer from accidentally editing the wrong file, especially when the code in adjacent opened files is very similar (and one is coding at 2 am to get a project finished).

Also, have the background color of the editor tab of an opened file set to read-only change to a different (user-definable in Settings?) color, to distinguish it from adjacent opened files that are editable. When the read-only restriction is toggled off, the normal background color of the editor tab should re-appear.