Note the layout here. The editor is being cut off.
Latest Chrome on MacBook. JCE editor selected (not your internal one)
Latest Chrome on MacBook. JCE editor selected (not your internal one)
I also found this Slide function of the settings bar very annoying while creating a post with some blocks.
I believe that Push will work better same as on current EB.
It behaves the same on built in composer and not only on JCE.
I was able to reproduce this in your demo site aswell.