settings: make initial slave screen focus optional

src/ncmpcpp.cpp

@@ -144,10 +144,16 @@ int main(int argc, char **argv)
 	// lock current screen and go to the slave one if applicable
 	if (Config.startup_slave_screen_type)
 	{
-		auto slave_screen = *Config.startup_slave_screen_type;
+		auto slave_screen_type = *Config.startup_slave_screen_type;
 		bool screen_locked = myScreen->lock();
-		if (screen_locked && slave_screen != myScreen->type())
-			toScreen(slave_screen)->switchTo();
+		if (screen_locked && slave_screen_type != myScreen->type())
+		{
+			auto slave_screen = toScreen(slave_screen_type);
+			assert(slave_screen != nullptr);
+			slave_screen->switchTo();
+			if (!Config.startup_slave_screen_focus)
+				Actions::get(Actions::Type::MasterScreen).execute();
+		}
 	}
 
 	// local variables

src/settings.cpp

@@ -546,6 +546,9 @@ bool Configuration::read(const std::vector<std::string> &config_paths, bool igno
 		}
 	}, defaults_to(startup_slave_screen_type, boost::none)
 	));
+	p.add("startup_slave_screen_focus", yes_no(
+		startup_slave_screen_focus, false
+	));
 	p.add("locked_screen_width_part", assign_default<double>(
 		locked_screen_width_part, 50.0, [](double v) {
 			return v / 100;

src/settings.h

@@ -165,6 +165,7 @@ struct Configuration
 	bool ask_for_locked_screen_width_part;
 	bool allow_for_physical_item_deletion;
 	bool progressbar_boldness;
+	bool startup_slave_screen_focus;
 
 	unsigned mpd_connection_timeout;
 	unsigned crossfade_time;