Feature: Added WindowOpener class, which prevents having duplicate windows of the same type opened at the same time

Wox/Helper/WindowOpener.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Windows;
+
+namespace Wox.Helper
+{
+	public static class WindowOpener
+	{
+		public static T Open<T>(params object[] args) where T : Window
+		{
+			var window = Application.Current.Windows.OfType<Window>().FirstOrDefault(x => x.GetType() == typeof(T))
+						 ?? (T)Activator.CreateInstance(typeof(T), args);
+			window.Show();
+			window.Focus();
+			Application.Current.MainWindow.Hide();
+			
+			return (T)window;
+		}
+	}
+}

Wox/MainWindow.xaml.cs

@@ -517,7 +517,7 @@ namespace Wox
 
         public void OpenSettingDialog()
         {
-            new SettingWindow(this).Show();
+	        WindowOpener.Open<SettingWindow>(this);
         }
 
         public void ShowCurrentResultItemTooltip(string text)

Wox/Wox.csproj

@@ -119,6 +119,7 @@
     <Compile Include="Helper\SyntaxSugars.cs" />
     <Compile Include="Helper\WallpaperPathRetrieval.cs" />
     <Compile Include="Helper\WindowIntelopHelper.cs" />
+    <Compile Include="Helper\WindowOpener.cs" />
     <Compile Include="OpacityModeConverter.cs" />
     <Compile Include="CustomPluginHotkeySetting.xaml.cs">
       <DependentUpon>CustomPluginHotkeySetting.xaml</DependentUpon>