Fuse IDE's Source tab shows the contents of a Apache Camel route file as XML.

This tab is useful for adding and editing any configuration, beans, or comments to the file. The Properties Editor can inspect the beans and use the information to populate editor fields that require bean references.

While the editor will allow you to change the contents of the camelContext element these changes are not preserved. Fuse IDE overwrites the camelContext element whenever changes are made using the Design tab.