In r5427, Simutrans crashes when you try to enlarge the map. This happens in all games (new and saved) I have tested so far.
The access violation happens at line 171 in gui_container.cc (gui_container_t::infowin_event). I also found out that the vfptr of komp points to 0xfeeefeee, i.e. it is uninitialized.
I cannot reproduce this :/
Can you provide a full call stack?
Can you upload a savegame to reproduce it?