Thanks a lot for your reply and I'll try the work around.

Regards,
Felix

I was too optimistic to write that it would take a week.
Digging into the code for several days, I understand that, unfortunately, I cannot do this.
Moving through 180 meridian creates too many places in the code, which can create an infinite loop and freeze the editor.
This should have been designed in the core, but I simple didn't think anyone would need this area.
So please accept my apologies, but this feature will not be implemented in the near future.
I'll write about this limitation in the documentation.

How to work around this limitation:
Generate two ares. The first is from 170 to 179.999999, the second is from -179.999999 to -170.

Thanks for the bug report.
I will try to fix the problem, but it will take some time (I think within a week) because this fix will require a lot of testing to avoid infinite loops and editor freezes.
I'll let you know when this is fixed.

  RWT is really a great tool, but I reached a problem when I try to create terrain across longitude 180 (e.g. From longitude 170 to longitude -170).  It show a error message "Bottom-right longitude must be greater than Top-Left Longitude".
  Could you tell me how to resolve this issue ?  Thanks a lot.

Regards,
Felix