I am currently working on a project and we came across an issue which we do not know how to resolve. We are updating the viewport with CodeMirror.MergeView. The code will be fully highlighted regardless of differences or not until we select one of the panels and start to type. As soon as you type or add a space the highlighting corrects is self. We also noticed that it works on Mac but not on Windows computers even though it is browser based.
If more information is needed I would be glad to explain in more detail.