Solved
This post I write with MS-Explorer.
With Chrom 73 this is not possible (rel 73 is a very new master release)
The text editor box accepts the input, but the text is not displayed in the update-modus.
When you send the post (with the not showing text) then he appears as new or updated post.
Environment: Windows 10 pro 64bit, Chrom:73.0.3683.75 (Offizieller Build) (64-Bit)
The same problem 
OK with Version 73.0.3683.67 (Official Build) beta (64-bit) (will update now...)
also OK for me with Version 73.0.3683.75 (Official Build) beta (64-bit)
However not working in Version 75.0.3731.0 (Official Build) canary (32-bit)
Thanks, That looks like a local bug in my computer (terrible).
Now, after delete all history (Cach, Cookies etc) it's works.
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