[Gimp-user] setting DPI for Gimp

[Helmut Jarausch <jarausch skynet be>]

Hi, since a short time I have a 27inch 4K Monitor which results in  162  
DPI.

xdpyinfo reports
  dimensions:    3840x2160 pixels (602x338 millimeters)
  resolution:    162x162 dots per inch

rr
But when Gimp displays something, e.g. a rectangle, reading the  
(displayed) rulers one can read the height and width of the rectangle,
but using an (external) ruler the displayed image (at 100%) is much  
larger, probably scaled by 162/96.
Thus, it looks like Gimp still uses 96DPI for displaying something.
How can I fix this?

Many thanks for a hint,
Helmut