diff --git a/src/newgrf_debug_gui.cpp b/src/newgrf_debug_gui.cpp
--- a/src/newgrf_debug_gui.cpp
+++ b/src/newgrf_debug_gui.cpp
@@ -507,6 +507,7 @@ static const NWidgetPart _nested_newgrf_
 		NWidget(WWT_CAPTION, COLOUR_GREY, WID_NGRFI_CAPTION), SetDataTip(STR_NEWGRF_INSPECT_CAPTION, STR_TOOLTIP_WINDOW_TITLE_DRAG_THIS),
 		NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_NGRFI_PARENT), SetDataTip(STR_NEWGRF_INSPECT_PARENT_BUTTON, STR_NEWGRF_INSPECT_PARENT_TOOLTIP),
 		NWidget(WWT_SHADEBOX, COLOUR_GREY),
+		NWidget(WWT_DEFSIZEBOX, COLOUR_GREY),
 		NWidget(WWT_STICKYBOX, COLOUR_GREY),
 	EndContainer(),
 	NWidget(NWID_HORIZONTAL),