r8163 Offset at selecting a line in lines window

[gauthier]

Simutrans rr8163 (120.2.2) with Linux 32 bits.

1. Open the line management window
2. Select any line: everything goes well
3. Select another line: the line below the line you pointed is selected
4. Select any line after: same behaviour

[Frank]

see http://simutrans-forum.de/forum/index.php?page=Thread&threadID=9329

fixed r8168

[gauthier]

Thanks