Differences between the source code currently being edited and corresponding stored source code can be indicated by different colored blocks alongside the vertical ruler of the editor window.
Displaying Quick Diff
To change the Quick Diff display settings:
Select "Window" > "Preferences" from the menu bar. The "Preferences" dialog box appears.
Select "General" > "Editor" > "Text Editors" > "Quick Diff" in the left pane. The "Quick Diff" page is displayed.
Change the Quick Diff settings as desired.
