diff --git a/src/group_gui.cpp b/src/group_gui.cpp
--- a/src/group_gui.cpp
+++ b/src/group_gui.cpp
@@ -87,6 +87,7 @@ static const NWidgetPart _nested_group_w
 	NWidget(NWID_HORIZONTAL), // Window header
 		NWidget(WWT_CLOSEBOX, COLOUR_GREY),
 		NWidget(WWT_CAPTION, COLOUR_GREY, GRP_WIDGET_CAPTION),
+		NWidget(WWT_SHADEBOX, COLOUR_GREY),
 		NWidget(WWT_STICKYBOX, COLOUR_GREY),
 	EndContainer(),
 	NWidget(NWID_HORIZONTAL),