Ok, now here comes the workaround:
http://github.com/potyl/gedit-scrollpaste
Emmanuel Rodriguez aka 'potyl' wrote a 'plugin' which fixes the scrolling when
pasting text with the mouse.
Unfortunately, it's placed in sourcecode only in a 'repository-style', which
means there's no configure script
Just found the bug upstream:
https://bugzilla.gnome.org/show_bug.cgi?id=575251
They think it's
Priority: Normal
Severity: minor
Seems to exist since 2.25 and was reported nearly a year ago (2009-03-13), but
is still 'unconfirmed' !!
Im thinking about simply using another editor...