This is an advanced editor that allows you to directly modify the component's XML.
It is a text editor with some built-in suggestions, giving access to the raw data used to build the component. Therefore, its use is only recommended if you have a thorough knowledge of the datamodel.
The bottom toolbar allows the user to increase/decrease the font size, and also to validate the XML file.
Assets management is a little bit tricky in this editor as it makes use of the items GUID.
In order to save a component, the XML must be first validated and then you can click on the Save button.