As discussed in http://forum.simutrans.com/index.php?topic=15256.msg150445#msg150445, still there is "no scroll bar issue" in extended setting window.
I found the bug point so I report it here.
At the end of settings_extended_general(revenue)_stats_t::init() function in gui/settings_stats.cc, there is
clear_dirty();
set_size( scr_size(width, ypos) );
but it does not work. We should write same as other functions like this:
clear_dirty();
height = ypos;
set_size( settings_stats_t::get_size() );
Then it worked well, the scroll bar appeared. Please fix this.
Thank you very much - I have now fixed this.