Created attachment 132631 [details]
Normally I have Main toolbar <Kate> and Main toolbar <KatePartView> like this:
I had two documents opened and I closed one and this caused KatePartView toolbar to disappear:
See attached sample video.
STEPS TO REPRODUCE
I had two files opened and I closed one.
Also when KatePartView wasn't visible and I clicked with mouse right button on document that I left open as in screenshot
no options appeared so I couldn't do copy with mouse. There wasn't mouse pop-up window.
KatePartView should be always visible. Mouse pop-up should always work.
Operating System: Manjaro Linux
KDE Plasma Version: 5.19.5
KDE Frameworks Version: 5.74.0
Qt Version: 5.15.1
Kernel Version: 5.4.72-1-MANJARO
OS Type: 64-bit
Processors: 2 × Intel® Core™2 Duo CPU E7400 @ 2.80GHz
Memory: 2.9 GiB of RAM
Graphics Processor: GeForce 210/PCIe/SSE2
I can't replicate this on kate from git master, my toolbar doesn't disappear. I was also able to right click in each document without issues.
Can you try on a new user on your system and see if the issue persists?
*** This bug has been marked as a duplicate of bug 426605 ***