Hi,
please look at the screenshot.
On the left side the searchpanel is cut.
Anyone who can confirm this?
Yes, you are right, with the folder tree on and a horizontal Find Panel and a vertical toolbar between the Folder Tree and the File Pane the Find Panel is cut:
Thanks Christiaan 
I sent a link to this post to GPsoftware.
I believe you will find that it is related to displaying a vertical toolbar. I saw this issue as soon as 9.1.2 came out. It's been reported, confirmed, and Jon is working diligently on it.
In the mean time, try closing all vertical toolbars. From what I saw, the utility panel will size correctly within a vertical file display window, so long as no vertical toolbars are displayed. Also, I could not get the issue to occur in a dual horizontal lister, with or without toolbars open.
You're right - closing my vertical toolbar fix it.
FWIW: You don't have to close your vertical toolbar: when you move it to the left of the foldertree, the utility panel will also size correctly:
Yes, but it doesn't look stylish 