Allow changing theme while in a game

changelog

@@ -27,6 +27,7 @@ Version 1.13.7+dev:
    * Improved Hotkey category sorting interface in Preferences.
    * Improved Addon Manager and MP Staging interfaces at low resolutions.
    * Fixed bug that allows you to use the minimap to bypass view locking
+   * You can now change the theme (in preferences) while a game is in progress.
  * WML Engine:
    * Add base_income key to [store_side]
    * Fix issues with alpha animations on hidden units (#14503)

data/gui/window/theme_list.cfg

@@ -55,23 +55,6 @@
 
 			[/row]
 
-			[row]
-				grow_factor = 0
-
-				[column]
-					border = "all"
-					border_size = 5
-					horizontal_alignment = "left"
-					[label]
-						definition = "default"
-						label = _ "The new theme will take effect after loading or starting a new game."
-						wrap = true
-					[/label]
-
-				[/column]
-
-			[/row]
-
 			[row]
 				grow_factor = 1
 

src/display.cpp

@@ -255,6 +255,13 @@ display::~display()
 	resources::fake_units = nullptr;
 }
 
+void display::set_theme(config theme_cfg) {
+	theme_ = theme(theme_cfg, screen_area());
+	menu_buttons_.clear();
+	action_buttons_.clear();
+	create_buttons();
+	invalidate_theme();
+}
 
 void display::init_flags() {
 

src/display.hpp

@@ -375,6 +375,7 @@ public:
 	void clear_redraw_observers();
 
 	theme& get_theme() { return theme_; }
+	void set_theme(config theme_cfg);
 
 	/**
 	 * Retrieves a pointer to a theme UI button.

src/preferences_display.cpp

@@ -34,6 +34,10 @@
 #include "gui/dialogs/transient_message.hpp"
 #include "gui/widgets/window.hpp"
 #include "log.hpp"
+#include "play_controller.hpp"
+#include "game_display.hpp"
+#include "game_config_manager.hpp"
+#include "resources.hpp"
 
 #include <boost/math/common_factor_rt.hpp>
 
@@ -120,9 +124,10 @@ bool show_theme_dialog(CVideo& video)
 	const int action = dlg.selected_index();
 
 	if (action >= 0) {
-		// FIXME: it would be preferable for the new theme to take effect
-		//        immediately.
 		preferences::set_theme(themes[action].id);
+		if(resources::screen && resources::controller) {
+			resources::screen->set_theme(resources::controller->get_theme(game_config_manager::get()->game_config(), themes[action].id));
+		}
 
 		return true;
 	}