I let you see what I see:
When I open any article in the German Wikipedia under Win7/IE, I see the above picture.
Syntax highlighting is obviously active. There is no icon, I don't know why. I have deleted my *css and *js yesterday, maybe this is the reason; it is opaque for the average user. Anyway, the icons were completely useless to me so I'm happy they are gone.
Now, assume I scroll down in the text and I want to edit the line where the cursor is.
If I click on the word "Eisenbahn" in the textbox, then
- the text displayed "jumps" to the beginning
- the scroll bar of the text box remains where the cursor is
- the user has to look for the cursor
Marking a text is practically impossible because at clicking, the focus is lost and the user does not see the text he wanted to mark any more.
This is extremely annoying (I read several complaints in discussions of the German wikipedia). I have not experienced this before syntax highlighting was introduced. If you are sure that syntax highlighting is not the cause of this issue, please channel this bug to the right place inside Wikimedia.
Given this bug, the only way to work efficiently for me is to copy the whole text into an external editor, carry out my edits, then copy the complete text back to the editing window.
However, when I copy such a text back from any text editor (I have tried several), syntax highlighting fails to highlight (no loss), but also saving or previewing fails to show the text pasted from the external editor but instead visualises the original text.
This means that at the moment, I can't contribute under Windows.
I don't know how many people experience this issue.
The implementation of syntax highlighting was very poorly communicated, it took me some time to find out the probable cause of these issues even though I consider myself a regular contributor.
For some reason, in English Wikipedia syntax highlighting seems to be "off" for me even though my user settings are identical.
Under Linux (Mint 19/Firefox), syntax highlighting is also obviously active. No icon, however.
Editing works fine.
Pasting text from a text editor (kate in my case) usually works, but I have observed the issue described above occasionally.