If Spaces / tabs are checked (enabled) in the View tab, this will display spaces and tabs as visible characters on the screen. It does not actually alter the contents of the file but allows you to clearly distinguish between the different characters.
With this option set:
·
»
If there is not enough room to show the '»' with the tab, the tab will appear as non-visible. The color used to display these characters can be configured in the Manage themes dialog.
See also: