[linux] Implement close method #56

Author: lijy91

example/lib/main.dart

@@ -1,3 +1,5 @@
+import 'dart:io';
+
 import 'package:flutter/material.dart';
 import 'package:bot_toast/bot_toast.dart';
 import 'package:window_manager/window_manager.dart';
@@ -11,7 +13,9 @@ void main() async {
   // Use it only after calling `hiddenWindowAtLaunch`
   windowManager.waitUntilReadyToShow().then((_) async {
     // Hide window title bar
-    await windowManager.setTitleBarStyle('hidden');
+    if (!Platform.isLinux) {
+      await windowManager.setTitleBarStyle('hidden');
+    }
     await windowManager.setSize(Size(800, 600));
     await windowManager.show();
     await windowManager.focus();

linux/window_manager_plugin.cc

@@ -69,6 +69,12 @@ static FlMethodResponse* set_as_frameless(WindowManagerPlugin* self,
       fl_method_success_response_new(fl_value_new_bool(true)));
 }
 
+static FlMethodResponse* close(WindowManagerPlugin* self) {
+  gtk_window_close(get_window(self));
+  return FL_METHOD_RESPONSE(
+      fl_method_success_response_new(fl_value_new_bool(true)));
+}
+
 static FlMethodResponse* focus(WindowManagerPlugin* self) {
   gtk_window_present(get_window(self));
   return FL_METHOD_RESPONSE(
@@ -377,6 +383,8 @@ static void window_manager_plugin_handle_method_call(
         fl_method_success_response_new(fl_value_new_bool(true)));
   } else if (strcmp(method, "setAsFrameless") == 0) {
     response = set_as_frameless(self, args);
+  } else if (strcmp(method, "close") == 0) {
+    response = close(self);
   } else if (strcmp(method, "focus") == 0) {
     response = focus(self);
   } else if (strcmp(method, "blur") == 0) {