Add quit launcher after game stops option (Steam Deck)

lecense

launcher/launch/steps/QuitAfterGameStop.h

@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-3.0-only
+/*
+ *  PolyMC - Minecraft Launcher
+ *  Copyright (C) 2022 dada513 <dada513@protonmail.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+
+class QuitAfterGameStop: public LaunchStep
+{
+    Q_OBJECT
+public:
+    explicit QuitAfterGameStop(LaunchTask *parent) :LaunchStep(parent){};
+    virtual ~QuitAfterGameStop() {};
+
+    virtual void executeTask();
+    virtual bool canAbort() const
+    {
+        return false;
+    }
+};