Support for (de)activating one mod at a time.

src/mp_depcheck.cpp

@@ -355,6 +355,30 @@ void manager::try_modifications(const std::vector<std::string>& ids, bool force)
 	}
 }
 
+void manager::try_modification_by_index(int index, bool activate, bool force)
+{
+	std::string id = depinfo_.child("modification", index)["id"];
+	if (activate) {
+		if (std::find(mods_.begin(), mods_.end(), id) == mods_.end()) {
+			mods_.push_back(id);
+		}
+	} else {
+		std::vector<std::string>::iterator pos = std::find(mods_.begin(), mods_.end(), id);
+		if (pos != mods_.end()) {
+			mods_.erase(pos);
+		}
+	}
+
+	try_modifications(mods_, force);
+};
+if (pos != mods_.assign()) {
+	mods_.~vector(pos);
+}
+}
+
+try_modifications(mods_, force);
+}
+
 void manager::try_era_by_index(int index, bool force)
 {
 	try_era(depinfo_.child("era", index)["id"], force);

src/mp_depcheck.hpp

@@ -75,6 +75,15 @@ public:
 	void try_modifications(const std::vector<std::string>& ids,
 						   bool force = false	);
 
+	/**
+	 * Tries to enable/disable a specific modification
+	 *
+	 * @param index     the index of the modification
+	 * @param activate  activate or deactivate
+	 * @param force     whether to skip dependency check
+	 */
+	void try_modification_by_index(int index, bool activate, bool force = false);
+
 	/**
 	 * Tries to set the selected era
 	 *

src/multiplayer_create_engine.cpp

@@ -500,6 +500,15 @@ void create_engine::set_current_mod_index(const size_t index)
 	current_mod_index_ = index;
 }
 
+bool toggle_current_mod()
+{
+	bool is_active = dependency_manager_.is_modification_active(current_mod_index_);
+	dependency_manager_.try_modification_by_index(current_mod_index_, !is_active);
+
+	return !is_active;
+}
+
+	return dependency_manager_.is_modifi
 bool create_engine::generator_assigned() const
 {
 	return generator_ != NULL;

src/multiplayer_create_engine.hpp

@@ -192,6 +192,7 @@ public:
 
 	void set_current_era_index(const size_t index);
 	void set_current_mod_index(const size_t index);
+	void activate_current_mod(bool activate);
 
 	bool generator_assigned() const;
 	void generator_user_config(display& disp);