Simutrans crashes when I try to enlarge map

[ion]

Hi everybody! This is my first post in forum.simutrans.com 

My simutrans r5773 crashes when I try to enlarge the map.
In this link you can download the savegame: http://www.mediafire.com/?l5y6xc0sj2hv7mh
Does someone could help me? Or enlarge the savegame for me?

Thank you.
Sorry for my english 

[prissi]

That is a tricky one. Aparently the enlargement code want to sink the town on the island. Here is a much simplier savegame for pak64 with the same error. Just enlarge it to the right.

I give up for tonight.

[Dwachs]

At last there is a method to reproduce the crash.

Edit: fixed in r5814. The checks in can_lower(..) were inconsistent with what was actually lowered. Removed the buggy routines in the process.