All I can tell you now is that the three tabs in right top corner are not visible.
After changing the default editor to TinyMCE or CodeMirror a message showed up that I could toogle the Editor, A button appeared in the right buttom under the editor field but nothing was clickable
I could not find any editor in Firefox debugger nor in chrome
all I can do now is to attach you my systeminfos
hope it helps
if you need further detail I can help again on wendesday...