diff --git a/src/textfile_gui.cpp b/src/textfile_gui.cpp
--- a/src/textfile_gui.cpp
+++ b/src/textfile_gui.cpp
@@ -27,6 +27,7 @@ static const NWidgetPart _nested_textfil
 	NWidget(NWID_HORIZONTAL),
 		NWidget(WWT_CLOSEBOX, COLOUR_MAUVE),
 		NWidget(WWT_CAPTION, COLOUR_MAUVE, WID_TF_CAPTION), SetDataTip(STR_NULL, STR_TOOLTIP_WINDOW_TITLE_DRAG_THIS),
+		NWidget(WWT_DEFSIZEBOX, COLOUR_MAUVE),
 	EndContainer(),
 	NWidget(NWID_HORIZONTAL),
 		NWidget(WWT_PANEL, COLOUR_MAUVE, WID_TF_BACKGROUND), SetMinimalSize(200, 125), SetResize(1, 12), SetScrollbar(WID_TF_VSCROLLBAR),