Eclipse has support for version control systems like Git, SVN and CVS. Support for Mercurial can be enabled by using the MercurialEclipse plugin. When viewing files in version control, it is common practice to quickly see which of the lines are uncommitted compared to the current head (or parent) revision. This information can be viewed in Eclipse by using its Quick Diff feature. This is easy to do:
Go to Window -> Preferences -> General -> Editors -> Text Editors -> Quick Diff. This is the dialog from where it can be configured.
Turn on Quick Diff, by enabling the option
Enable quick diff.
Choose the version control system for which Quick Diff is needed from the dropdown
Use this reference source. Git, SVN and CVS should be present here. Mercurial appears if the MercurialEclipse plugin is installed.
The overview ruler is the ruler to the right of the scrollbar in the editor. If you would like to see the uncommitted lines to be marked on it, enable the option
Show differences in overview ruler.
Choose Apply and OK. Close all editor windows and reopen the source file that you want in the editor.
You should be able to see the newly added, modified or deleted lines marked in colors in the left bar on which line numbers are usually displayed. The colors used are the ones set in the Quick Diff dialog (see above steps). You can also view these uncommitted locations marked along the overview ruler on the right.
Tried with: Eclipse Luna 4.4.1 and Ubuntu 14.04