Re: how to autohide the panel?

I haven't had this issue on any of my machines, but have you tried re-creating 
the panel, or wayland vs X11? It looks like there are a few similar bug 
reports[1], but I imagine this issue may be present for different reasons on 
different systems. It may be worth checking system logs also. And not to get 
off topic, but I'd be interested to know what problems you're having with 
kmail? My experience has been really good with it.

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[1] https://bugs.kde.org/buglist.cgi?
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