Add Custom Highlights to Content
Question
How can we add custom highlights to the document content in Author mode?
Answer
There are two types of highlights you can add:
- Non-Persistent Highlights - Such highlights are removed when the document is
                     closed and then re-opened.
                     You can use the following API method: ro.sync.exml.workspace.api.editor.page.author.WSAuthorEditorPageBase.getHighlighter()to obtain an AuthorHighlighter that allows you to add a highlight between certain offsets with a specified painter. For example, you can use this support to implement your own spell checker with a custom highlight for the unrecognized words. 
- Persistent Highlights - Such highlights are saved in the XML content as
                     processing instructions.
                     You can use the following API method: ro.sync.exml.workspace.api.editor.page.author.WSAuthorEditorPageBase.getPersistentHighlighter()to obtain an AuthorPersistentHighlighter class that allows you to add a persistent highlight between certain offsets, set new properties for a specific highlight, and render it with a specified painter. For example, you can use this support to implement your own way of adding review comments. 
