diff --git a/src/main_gui.cpp b/src/main_gui.cpp
index 36cda036bf..6eaab74e66 100644
--- a/src/main_gui.cpp
+++ b/src/main_gui.cpp
@@ -217,7 +217,7 @@ extern void UpdateAllStationVirtCoord();
 
 struct MainWindow : Window
 {
-	MainWindow(int width, int height) : Window(0, 0, width, height, NULL, WC_MAIN_WINDOW, NULL)
+	MainWindow(int width, int height) : Window(0, 0, width, height, WC_MAIN_WINDOW, NULL)
 	{
 		InitializeWindowViewport(this, 0, 0, width, height, TileXY(32, 32), ZOOM_LVL_VIEWPORT);
 	}
diff --git a/src/misc_gui.cpp b/src/misc_gui.cpp
index 3eb985d9f0..d2d306af93 100644
--- a/src/misc_gui.cpp
+++ b/src/misc_gui.cpp
@@ -352,7 +352,7 @@ private:
 
 public:
 	ErrmsgWindow(Point pt, int width, int height, StringID msg1, StringID msg2, const Widget *widget, bool show_player_face) :
-			Window(pt.x, pt.y, width, height, NULL, WC_ERRMSG, widget),
+			Window(pt.x, pt.y, width, height, WC_ERRMSG, widget),
 			show_player_face(show_player_face)
 	{
 		this->duration = _patches.errmsg_duration;
@@ -532,7 +532,7 @@ struct TooltipsWindow : public Window
 
 	TooltipsWindow(int x, int y, int width, int height, const Widget *widget,
 								 StringID str, uint paramcount, const uint64 params[]) :
-			Window(x, y, width, height, NULL, WC_TOOLTIPS, widget)
+			Window(x, y, width, height, WC_TOOLTIPS, widget)
 	{
 		this->string_id = str;
 		assert(sizeof(this->params[0]) == sizeof(params[0]));
diff --git a/src/network/network_gui.cpp b/src/network/network_gui.cpp
index d92ee5aac8..49542410f1 100644
--- a/src/network/network_gui.cpp
+++ b/src/network/network_gui.cpp
@@ -1321,7 +1321,7 @@ struct NetworkClientListPopupWindow : Window {
 	ClientList_Action_Proc *proc[MAX_CLIENTLIST_ACTION];
 
 	NetworkClientListPopupWindow(int x, int y, const Widget *widgets, int client_no) :
-			Window(x, y, 150, 100, NULL, WC_TOOLBAR_MENU, widgets),
+			Window(x, y, 150, 100, WC_TOOLBAR_MENU, widgets),
 			sel_index(0), client_no(client_no)
 	{
 		/*
diff --git a/src/toolbar_gui.cpp b/src/toolbar_gui.cpp
index 0a3be270e4..b41b6c1d7b 100644
--- a/src/toolbar_gui.cpp
+++ b/src/toolbar_gui.cpp
@@ -1125,7 +1125,7 @@ struct ToolbarMenuWindow : Window {
 	ToolbarMenuWindow(int x, int y, int width, int height, const Widget *widgets, int item_count,
 										int sel_index, int parent_button, StringID base_string, int checked_items,
 										int disabled_mask) :
-			Window(x, y, width, height, NULL, WC_TOOLBAR_MENU, widgets),
+			Window(x, y, width, height, WC_TOOLBAR_MENU, widgets),
 			item_count(item_count), sel_index(sel_index), main_button(GB(parent_button, 0, 8)),
 			action_id((GB(parent_button, 8, 8) != 0) ? GB(parent_button, 8, 8) : parent_button),
 			checked_items(checked_items), disabled_items(disabled_items), base_string(base_string)
@@ -1280,7 +1280,7 @@ struct ToolbarPlayerMenuWindow : Window {
 	int gray_items;
 
 	ToolbarPlayerMenuWindow(int x, int y, int width, int height, const Widget *widgets, int main_button, int gray) :
-			Window(x, y, width, height, NULL, WC_TOOLBAR_MENU, widgets),
+			Window(x, y, width, height, WC_TOOLBAR_MENU, widgets),
 			item_count(0), main_button(main_button), action_id(main_button), gray_items(gray)
 	{
 		this->flags4 &= ~WF_WHITE_BORDER_MASK;
diff --git a/src/widgets/dropdown.cpp b/src/widgets/dropdown.cpp
index 67cb77b890..b9857ddaf0 100644
--- a/src/widgets/dropdown.cpp
+++ b/src/widgets/dropdown.cpp
@@ -72,7 +72,7 @@ struct DropdownWindow : Window {
 	bool drag_mode;
 	int scrolling;
 
-	DropdownWindow(int x, int y, int width, int height, const Widget *widget) : Window(x, y, width, height, NULL, WC_DROPDOWN_MENU, widget)
+	DropdownWindow(int x, int y, int width, int height, const Widget *widget) : Window(x, y, width, height, WC_DROPDOWN_MENU, widget)
 	{
 	}
 
diff --git a/src/window.cpp b/src/window.cpp
index 5e6a2f1b9a..4f5e1cc7aa 100644
--- a/src/window.cpp
+++ b/src/window.cpp
@@ -963,16 +963,13 @@ void Window::FindWindowPlacementAndResize(const WindowDesc *desc)
  * @param y offset in pixels from the top of the screen
  * @param width width in pixels of the window
  * @param height height in pixels of the window
- * @param *proc see WindowProc function to call when any messages/updates happen to the window
  * @param cls see WindowClass class of the window, used for identification and grouping
  * @param *widget see Widget pointer to the window layout and various elements
  * @return Window pointer of the newly created window
  */
-Window::Window(int x, int y, int width, int height, WindowProc *proc, WindowClass cls, const Widget *widget)
+Window::Window(int x, int y, int width, int height, WindowClass cls, const Widget *widget)
 {
-	this->Initialize(x, y, width, height, proc, cls, widget, 0);
-
-	if (proc != NULL) this->FindWindowPlacementAndResize(width, height);
+	this->Initialize(x, y, width, height, NULL, cls, widget, 0);
 }
 
 
diff --git a/src/window_gui.h b/src/window_gui.h
index f1e8ed21f4..66ce5a0eb7 100644
--- a/src/window_gui.h
+++ b/src/window_gui.h
@@ -282,7 +282,7 @@ protected:
 	void FindWindowPlacementAndResize(const WindowDesc *desc);
 
 public:
-	Window(int x, int y, int width, int height, WindowProc *proc, WindowClass cls, const Widget *widget);
+	Window(int x, int y, int width, int height, WindowClass cls, const Widget *widget);
 	Window(const WindowDesc *desc, WindowNumber number = 0);
 
 	virtual ~Window();