Edwin, I could not find a solution for this. As a workaround the CKEEditor is used.
I have the same issue (in others several other browsers), showing this error '404 - file not found for file: ui/yui/reset-fonts.css' in the console.
Any solutions found?
Thijs is right, use the CKEditor instead. If you look at the documentation of the RichTextSuite, you see:
This widget is based on a legacy library and isn't actively supported. Please use CKEditor widget for text editor requirements in your project.
We provide the source of the RichTextSuite on Github, if someone wants to maintain it. This widget is a few years old and not supported, it contains a lot of legacy code.
Much problems are caused by the Rich Text Editor. CKEditor solves them I experienced.