Восстанавливаемся при повторном запуске

.semver.txt

@@ -1 +1 @@
-1.0.32
+1.0.33

src/JiraTimeBot/JiraTimeBot.csproj

@@ -116,6 +116,7 @@
     <Compile Include="UI\frmSettings.Designer.cs">
       <DependentUpon>frmSettings.cs</DependentUpon>
     </Compile>
+    <Compile Include="UI\Tray\SingleInstance.cs" />
     <Compile Include="UI\Tray\ITrayMenu.cs" />
     <Compile Include="UI\Tray\RestoreFromTray.cs" />
     <Compile Include="UI\Tray\TrayMenu.cs" />

src/JiraTimeBot/Program.cs

@@ -4,6 +4,7 @@ using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Threading;
 using System.Windows.Forms;
+using JiraTimeBot.UI.Tray;
 
 namespace JiraTimeBot
 {
@@ -25,7 +26,7 @@ namespace JiraTimeBot
             }
             else
             {
-                MessageBox.Show("Another instance of the app is already running.");
+                SingleInstance.ShowFirstInstance();
             }
         }
     }

src/JiraTimeBot/Properties/AssemblyInfo.cs

@@ -26,6 +26,6 @@ using System.Runtime.InteropServices;
 //                        
 // You can specify all the values or you can default the Build and Revision Numbers                        
 // by using the '*' as shown below:                        
-[assembly: AssemblyVersion("1.0.32")] 
-[assembly: AssemblyFileVersion("1.0.32")] 
-[assembly: AssemblyInformationalVersion("1.0.32")] 
+[assembly: AssemblyVersion("1.0.33")] 
+[assembly: AssemblyFileVersion("1.0.33")] 
+[assembly: AssemblyInformationalVersion("1.0.33")] 

src/JiraTimeBot/UI/Tray/SingleInstance.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Reflection;
+using System.Runtime.InteropServices;
+
+namespace JiraTimeBot.UI.Tray
+{
+    static class SingleInstance
+    {
+        public static readonly int WM_SHOWFIRSTINSTANCE = RegisterWindowMessage($"WM_SHOWFIRSTINSTANCE|{AssemblyGuid}");
+        
+        public static void ShowFirstInstance()
+        {
+            const int HWND_BROADCAST = 0xffff;
+            PostMessage((IntPtr)HWND_BROADCAST, WM_SHOWFIRSTINSTANCE, IntPtr.Zero, IntPtr.Zero);
+        }
+        
+        public static string AssemblyGuid
+        {
+            get
+            {
+                object[] attributes = Assembly.GetEntryAssembly().GetCustomAttributes(typeof(System.Runtime.InteropServices.GuidAttribute), false);
+                if (attributes.Length == 0) {
+                    return string.Empty;
+                }
+                return ((GuidAttribute)attributes[0]).Value;
+            }
+        }
+        
+        [DllImport("user32")]
+        public static extern int RegisterWindowMessage(string message);
+	
+        [DllImport("user32")]
+        public static extern bool PostMessage(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam);
+    }
+}

src/JiraTimeBot/UI/frmMain.cs

@@ -31,6 +31,16 @@ namespace JiraTimeBot.UI
         private readonly Action<string> _settingsErrorReporter;
         private bool _updateChecked;
 
+        protected override void WndProc(ref Message message)
+        {
+            if (message.Msg == SingleInstance.WM_SHOWFIRSTINSTANCE) {
+                this.Show();
+                this.WindowState = FormWindowState.Normal;
+                _trayIcon.Hide();
+            }
+            base.WndProc(ref message);
+        }
+
         private CancellationTokenSource GetTokenSource()
         {
             var tokenSource = new CancellationTokenSource();