Remove the option to disable the mdi feature of the editor.

data/gui/default/window/editor_settings.cfg

@@ -214,27 +214,6 @@
 					[/label]
 				[/column]
 			[/row]
-			[row]
-				grow_factor = 0
-				[column]
-					horizontal_alignment = "left"
-					[grid]
-						[row]
-							grow_factor = 0
-							[column]
-								border = "all"
-								border_size = 5
-								horizontal_alignment = "left"
-								[toggle_button]
-									id = "use_mdi"
-									definition = "default"
-									label = _ "Allow multiple maps to be open simultaneously"
-								[/toggle_button]
-							[/column]
-						[/row]
-					[/grid]
-				[/column]
-			[/row]
 			[row]
 				grow_factor = 0
 				[column]

src/editor/editor_preferences.cpp

@@ -29,14 +29,6 @@ namespace editor {
 		preferences::set("editor_auto_update_transitions", lexical_cast<std::string>(value));
 	}
 
-	bool use_mdi() {
-		return preferences::get("editor_use_mdi", true);
-	}
-
-	void set_use_mdi(bool value) {
-		preferences::set("editor_use_mdi", value);
-	}
-
 	std::string default_dir() {
 		return preferences::get("editor_default_dir");
 	}

src/editor/editor_preferences.hpp

@@ -31,9 +31,6 @@ namespace editor {
 	int auto_update_transitions();
 	void set_auto_update_transitions(int value);
 
-	bool use_mdi();
-	void set_use_mdi(bool value);
-
 	std::string default_dir();
 
 	bool draw_terrain_codes();

src/editor/map/context_manager.cpp

@@ -169,33 +169,23 @@ void context_manager::set_default_dir(const std::string& str)
 
 void context_manager::load_map_dialog(bool force_same_context /* = false */)
 {
-	if (!preferences::editor::use_mdi() && !confirm_discard()) {
-		return;
-	}
-
 	std::string fn = directory_name(get_map_context().get_filename());
 	if (fn.empty()) {
 		fn = default_dir_;
 	}
 	int res = dialogs::show_file_chooser_dialog(gui_, fn, _("Choose a Map to Open"));
 	if (res == 0) {
-		load_map(fn, force_same_context
-				? false
-				: preferences::editor::use_mdi());
+		load_map(fn, !force_same_context);
 	}
 }
 
 void context_manager::new_map_dialog()
 {
-	if (!preferences::editor::use_mdi() && !confirm_discard()) {
-		return;
-	}
-
 	int w = get_map().w();
 	int h = get_map().h();
 	if(gui2::teditor_new_map::execute(w, h, gui_.video())) {
 		const t_translation::t_terrain fill = get_selected_bg_terrain();
-		new_map(w, h, fill, preferences::editor::use_mdi());
+		new_map(w, h, fill, true);
 	}
 }
 

src/gui/dialogs/editor_settings.cpp

@@ -99,10 +99,6 @@ teditor_settings::teditor_settings(editor::editor_display* display
 	, display_(display)
 	, can_update_display_(false)
 {
-	register_bool("use_mdi"
-			, true
-			, &preferences::editor::use_mdi
-			, &preferences::editor::set_use_mdi);
 }
 
 void teditor_settings::do_next_tod(twindow& window)