Highlighting a map object allows you to edit its label, as well as any notes and messages attached to it. You can only highlight one map object at a time. The default configuration for highlighting a map object is a single click on the map object you want to highlight. You can tell a map object is highlighted, because it will have a line drawn around it.
Note: A single click to highlight is the default configuration. You can configure highlight to occur with a Ctrl + Click, by selecting that option in Edit>Application Settings>Mouse. See Configure Mouse Properties for more information.