Terrains from image file in Build 17

[CarlS]

Terrains created with an imported image vanish when the Generate button is pressed.
This works in GeoControl 1.

Steps to Reproduce
(1) Start the program, generate a default terrain
(2) Click on Generation > Terrain Import > Image Import
(3) Using the browser, find and select an image, then press OK
(4) The image show in the terrain view
(5) Click the Generate button
(6) The terrain is cleared, only a smooth flat plane remains

[cajomi]

Do not forget to adjust the protection slider, to decide from what level the generation should start.
Simplest way with imported terrains: Only use the Postwork section.