diff --git a/src/signs_gui.cpp b/src/signs_gui.cpp
--- a/src/signs_gui.cpp
+++ b/src/signs_gui.cpp
@@ -149,11 +149,11 @@ struct SignListWindow : Window, SignList
 	int text_offset; ///< Offset of the sign text relative to the left edge of the WID_SIL_LIST widget.
 	Scrollbar *vscroll;
 
-	SignListWindow(const WindowDesc *desc, WindowNumber window_number) : filter_editbox(MAX_LENGTH_SIGN_NAME_CHARS * MAX_CHAR_LENGTH, MAX_LENGTH_SIGN_NAME_CHARS)
+	SignListWindow(WindowDesc *desc, WindowNumber window_number) : Window(desc), filter_editbox(MAX_LENGTH_SIGN_NAME_CHARS * MAX_CHAR_LENGTH, MAX_LENGTH_SIGN_NAME_CHARS)
 	{
-		this->CreateNestedTree(desc);
+		this->CreateNestedTree();
 		this->vscroll = this->GetScrollbar(WID_SIL_SCROLLBAR);
-		this->FinishInitNested(desc, window_number);
+		this->FinishInitNested(window_number);
 		this->SetWidgetLoweredState(WID_SIL_FILTER_MATCH_CASE_BTN, SignList::match_case);
 
 		/* Initialize the text edit widget */
@@ -369,7 +369,7 @@ static const NWidgetPart _nested_sign_li
 	EndContainer(),
 };
 
-static const WindowDesc _sign_list_desc(
+static WindowDesc _sign_list_desc(
 	WDP_AUTO, 358, 138,
 	WC_SIGN_LIST, WC_NONE,
 	0,
@@ -412,14 +412,14 @@ struct SignWindow : Window, SignList {
 	QueryString name_editbox;
 	SignID cur_sign;
 
-	SignWindow(const WindowDesc *desc, const Sign *si) : name_editbox(MAX_LENGTH_SIGN_NAME_CHARS * MAX_CHAR_LENGTH, MAX_LENGTH_SIGN_NAME_CHARS)
+	SignWindow(WindowDesc *desc, const Sign *si) : Window(desc), name_editbox(MAX_LENGTH_SIGN_NAME_CHARS * MAX_CHAR_LENGTH, MAX_LENGTH_SIGN_NAME_CHARS)
 	{
 		this->querystrings[WID_QES_TEXT] = &this->name_editbox;
 		this->name_editbox.caption = STR_EDIT_SIGN_CAPTION;
 		this->name_editbox.cancel_button = WID_QES_CANCEL;
 		this->name_editbox.ok_button = WID_QES_OK;
 
-		this->InitNested(desc, WN_QUERY_STRING_SIGN);
+		this->InitNested(WN_QUERY_STRING_SIGN);
 
 		UpdateSignEditWindow(si);
 		this->SetFocusedWidget(WID_QES_TEXT);
@@ -531,7 +531,7 @@ static const NWidgetPart _nested_query_s
 	EndContainer(),
 };
 
-static const WindowDesc _query_sign_edit_desc(
+static WindowDesc _query_sign_edit_desc(
 	WDP_AUTO, 0, 0,
 	WC_QUERY_STRING, WC_NONE,
 	WDF_CONSTRUCTION,