Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.
Your bug report will be posted to the emacs-pretest-bug@gnu.org mailing
list.
Please describe exactly what actions triggered the bug
and the precise symptoms of the bug. If you can, give
a recipe starting from `emacs -Q':
1. Start the Gtk+ build of emacs.
2. Visit a file too big to fit in the window.
3. Drag the (vertical) scrollbar thumb.
4. Scroll through the buffer using the mouse wheel or keystrokes.
The scrollbar thumb stays fixed and no longer shows the relative
position in the buffer. Clicking in an empty area of the scrollbar
restores the correct behavior.