diff --git a/src/genworld_gui.cpp b/src/genworld_gui.cpp
--- a/src/genworld_gui.cpp
+++ b/src/genworld_gui.cpp
@@ -797,14 +797,14 @@ struct GenerateLandscapeWindow : public 
 };
 
 static WindowDesc _generate_landscape_desc(
-	WDP_CENTER, 0, 0,
+	WDP_CENTER, NULL, 0, 0,
 	WC_GENERATE_LANDSCAPE, WC_NONE,
 	0,
 	_nested_generate_landscape_widgets, lengthof(_nested_generate_landscape_widgets)
 );
 
 static WindowDesc _heightmap_load_desc(
-	WDP_CENTER, 0, 0,
+	WDP_CENTER, NULL, 0, 0,
 	WC_GENERATE_LANDSCAPE, WC_NONE,
 	0,
 	_nested_heightmap_load_widgets, lengthof(_nested_heightmap_load_widgets)
@@ -1098,7 +1098,7 @@ static const NWidgetPart _nested_create_
 };
 
 static WindowDesc _create_scenario_desc(
-	WDP_CENTER, 0, 0,
+	WDP_CENTER, NULL, 0, 0,
 	WC_GENERATE_LANDSCAPE, WC_NONE,
 	0,
 	_nested_create_scenario_widgets, lengthof(_nested_create_scenario_widgets)
@@ -1126,7 +1126,7 @@ static const NWidgetPart _nested_generat
 
 
 static WindowDesc _generate_progress_desc(
-	WDP_CENTER, 0, 0,
+	WDP_CENTER, NULL, 0, 0,
 	WC_MODAL_PROGRESS, WC_NONE,
 	0,
 	_nested_generate_progress_widgets, lengthof(_nested_generate_progress_widgets)