Changed lines
If the option is enabled, the editor shows colored indicators on the left side of modified lines.
Indicators for modified lines drawn in color Changed Indicator, modified+saved lines drawn in Changed and Saved Indicator color. Colors can be modified for syntax in Fonts and Colors settings.
The option can be switched on as for single document in View→Editor (file specific)→Changed Lines as for all documents of specific syntax.
If Line Numbers margin is enabled, changed lines information is shown there, but not in dedicated area.