[scribus] Why to I have to set the screen size in Scribus?

[Philipp Klaus Krause]

I just noticed that sizes were not correct in Scribus by default (when I
held a ruler to the screen it didn't match with the Scribus one).
I found the monitor configuration option where I can set the DPI to
correct this and did so.
Why doesn't Scribus do this automatically? It should just use the value
it gets from the Window system (like other applications, e.g. gimp do)
by default, so I don't have to configure this for every application
individually.

Philipp