I've set up my Raspberry in that way, that it opens up Midori on start up. Midori then loads a html page in full screen mode. Everything works as expected.
But I also specified a refresh interval with the parameter
-i 3600. The problem occurs after the first refresh of the page because after that refresh is the navigation bar shown.
Someone had the same problem here: Raspberry Pi Forum.
His solution was to switch from Midori to Minimal Kiosk Browser (kweb). But I don't want to do this.
So is there a way to hide the navigation bar after a refresh?