Add ConnectionFrameColor feature for visual environment distinction

- Added ConnectionFrameColor enum with None, Red, Yellow, Green, Blue, Purple options
- Added ConnectionFrameColor property to AbstractConnectionRecord with inheritance support
- Updated XML serialization to save/load ConnectionFrameColor
- Added language resources for ConnectionFrameColor
- Implemented visual border rendering in InterfaceControl based on ConnectionFrameColor

Co-authored-by: Kvarkas <3611964+Kvarkas@users.noreply.github.com>

mRemoteNG/Config/Serializers/ConnectionSerializers/Xml/XmlConnectionNodeSerializer28.cs

@@ -43,6 +43,7 @@ namespace mRemoteNG.Config.Serializers.ConnectionSerializers.Xml
             element.Add(new XAttribute("Icon", connectionInfo.Icon));
             element.Add(new XAttribute("Panel", connectionInfo.Panel));
             element.Add(new XAttribute("TabColor", connectionInfo.TabColor));
+            element.Add(new XAttribute("ConnectionFrameColor", connectionInfo.ConnectionFrameColor));
             element.Add(new XAttribute("Id", connectionInfo.ConstantID));
 
             if (!Runtime.UseCredentialManager)
@@ -195,6 +196,8 @@ namespace mRemoteNG.Config.Serializers.ConnectionSerializers.Xml
                 element.Add(new XAttribute("InheritPanel", inheritance.Panel.ToString().ToLowerInvariant()));
             if (inheritance.TabColor)
                 element.Add(new XAttribute("InheritTabColor", inheritance.TabColor.ToString().ToLowerInvariant()));
+            if (inheritance.ConnectionFrameColor)
+                element.Add(new XAttribute("InheritConnectionFrameColor", inheritance.ConnectionFrameColor.ToString().ToLowerInvariant()));
             if (inheritance.Password)
                 element.Add(new XAttribute("InheritPassword", inheritance.Password.ToString().ToLowerInvariant()));
             if (inheritance.Port)

mRemoteNG/Config/Serializers/ConnectionSerializers/Xml/XmlConnectionsDeserializer.cs

@@ -328,6 +328,7 @@ namespace mRemoteNG.Config.Serializers.ConnectionSerializers.Xml
                     connectionInfo.Inheritance.Icon = xmlnode.GetAttributeAsBool("InheritIcon");
                     connectionInfo.Inheritance.Panel = xmlnode.GetAttributeAsBool("InheritPanel");
                     connectionInfo.Inheritance.TabColor = xmlnode.GetAttributeAsBool("InheritTabColor");
+                    connectionInfo.Inheritance.ConnectionFrameColor = xmlnode.GetAttributeAsBool("InheritConnectionFrameColor");
                     connectionInfo.Inheritance.Port = xmlnode.GetAttributeAsBool("InheritPort");
                     connectionInfo.Inheritance.Protocol = xmlnode.GetAttributeAsBool("InheritProtocol");
                     connectionInfo.Inheritance.PuttySession = xmlnode.GetAttributeAsBool("InheritPuttySession");
@@ -351,6 +352,7 @@ namespace mRemoteNG.Config.Serializers.ConnectionSerializers.Xml
                     connectionInfo.Icon = xmlnode.GetAttributeAsString("Icon");
                     connectionInfo.Panel = xmlnode.GetAttributeAsString("Panel");
                     connectionInfo.TabColor = xmlnode.GetAttributeAsString("TabColor");
+                    connectionInfo.ConnectionFrameColor = xmlnode.GetAttributeAsEnum<ConnectionFrameColor>("ConnectionFrameColor");
                 }
                 else
                 {

mRemoteNG/Connection/AbstractConnectionRecord.cs

@@ -25,6 +25,7 @@ namespace mRemoteNG.Connection
         private string _panel;
         private string _color;
         private string _tabColor;
+        private ConnectionFrameColor _connectionFrameColor;
 
         private string _hostname;
         private ExternalAddressProvider _externalAddressProvider;
@@ -181,6 +182,16 @@ namespace mRemoteNG.Connection
             set => SetField(ref _tabColor, value, "TabColor");
         }
 
+        [LocalizedAttributes.LocalizedCategory(nameof(Language.Display)),
+         LocalizedAttributes.LocalizedDisplayName(nameof(Language.ConnectionFrameColor)),
+         LocalizedAttributes.LocalizedDescription(nameof(Language.PropertyDescriptionConnectionFrameColor)),
+         TypeConverter(typeof(MiscTools.EnumTypeConverter))]
+        public virtual ConnectionFrameColor ConnectionFrameColor
+        {
+            get => GetPropertyValue("ConnectionFrameColor", _connectionFrameColor);
+            set => SetField(ref _connectionFrameColor, value, "ConnectionFrameColor");
+        }
+
         #endregion
 
         #region Connection

mRemoteNG/Connection/ConnectionFrameColor.cs

@@ -0,0 +1,26 @@
+using mRemoteNG.Tools;
+using mRemoteNG.Resources.Language;
+
+namespace mRemoteNG.Connection
+{
+    public enum ConnectionFrameColor
+    {
+        [LocalizedAttributes.LocalizedDescription(nameof(Language.FrameColorNone))]
+        None = 0,
+
+        [LocalizedAttributes.LocalizedDescription(nameof(Language.FrameColorRed))]
+        Red = 1,
+
+        [LocalizedAttributes.LocalizedDescription(nameof(Language.FrameColorYellow))]
+        Yellow = 2,
+
+        [LocalizedAttributes.LocalizedDescription(nameof(Language.FrameColorGreen))]
+        Green = 3,
+
+        [LocalizedAttributes.LocalizedDescription(nameof(Language.FrameColorBlue))]
+        Blue = 4,
+
+        [LocalizedAttributes.LocalizedDescription(nameof(Language.FrameColorPurple))]
+        Purple = 5
+    }
+}

mRemoteNG/Connection/ConnectionInfo.cs

@@ -294,6 +294,7 @@ namespace mRemoteNG.Connection
             Panel = Language.General;
             Color = string.Empty;
             TabColor = string.Empty;
+            ConnectionFrameColor = ConnectionFrameColor.None;
         }
 
         private void SetConnectionDefaults()

mRemoteNG/Connection/ConnectionInfoInheritance.cs

@@ -62,6 +62,12 @@ namespace mRemoteNG.Connection
          TypeConverter(typeof(MiscTools.YesNoTypeConverter))]
         public bool TabColor { get; set; }
 
+        [LocalizedAttributes.LocalizedCategory(nameof(Language.Display), 2),
+         LocalizedAttributes.LocalizedDisplayNameInherit(nameof(Language.ConnectionFrameColor)),
+         LocalizedAttributes.LocalizedDescriptionInherit(nameof(Language.PropertyDescriptionConnectionFrameColor)),
+         TypeConverter(typeof(MiscTools.YesNoTypeConverter))]
+        public bool ConnectionFrameColor { get; set; }
+
         #endregion
 
         #region Connection

mRemoteNG/Connection/InterfaceControl.cs

@@ -32,6 +32,9 @@ namespace mRemoteNG.Connection
                 Size = Parent.Size;
                 Anchor = AnchorStyles.Bottom | AnchorStyles.Left | AnchorStyles.Right | AnchorStyles.Top;
                 InitializeComponent();
+                
+                // Enable custom painting for border
+                this.Paint += InterfaceControl_Paint;
             }
             catch (Exception ex)
             {
@@ -41,6 +44,41 @@ namespace mRemoteNG.Connection
             }
         }
 
+        private void InterfaceControl_Paint(object sender, PaintEventArgs e)
+        {
+            // Draw colored border based on ConnectionFrameColor property
+            if (Info?.ConnectionFrameColor != null && Info.ConnectionFrameColor != ConnectionFrameColor.None)
+            {
+                Color frameColor = GetFrameColor(Info.ConnectionFrameColor);
+                int borderWidth = 4; // 4 pixel border for visibility
+                
+                using (Pen pen = new Pen(frameColor, borderWidth))
+                {
+                    // Draw border inside the control bounds
+                    Rectangle rect = new Rectangle(
+                        borderWidth / 2,
+                        borderWidth / 2,
+                        this.Width - borderWidth,
+                        this.Height - borderWidth
+                    );
+                    e.Graphics.DrawRectangle(pen, rect);
+                }
+            }
+        }
+
+        private Color GetFrameColor(ConnectionFrameColor frameColor)
+        {
+            return frameColor switch
+            {
+                ConnectionFrameColor.Red => Color.FromArgb(220, 53, 69),      // Bootstrap danger red
+                ConnectionFrameColor.Yellow => Color.FromArgb(255, 193, 7),   // Warning yellow
+                ConnectionFrameColor.Green => Color.FromArgb(40, 167, 69),    // Success green
+                ConnectionFrameColor.Blue => Color.FromArgb(0, 123, 255),     // Primary blue
+                ConnectionFrameColor.Purple => Color.FromArgb(111, 66, 193),  // Purple
+                _ => Color.Transparent
+            };
+        }
+
         public static InterfaceControl FindInterfaceControl(DockPanel DockPnl)
         {
             // instead of repeating the code, call the routine using ConnectionTab if called by DockPanel

mRemoteNG/Language/Language.resx

@@ -2517,4 +2517,28 @@ Nightly Channel includes Alphas, Betas &amp; Release Candidates.</value>
     <value>Community</value>
     <comment>Reddit</comment>
   </data>
+  <data name="ConnectionFrameColor" xml:space="preserve">
+    <value>Connection Frame Color</value>
+  </data>
+  <data name="PropertyDescriptionConnectionFrameColor" xml:space="preserve">
+    <value>Sets a colored border around the connection panel to visually distinguish between different environments (e.g., production, test, development).</value>
+  </data>
+  <data name="FrameColorNone" xml:space="preserve">
+    <value>None</value>
+  </data>
+  <data name="FrameColorRed" xml:space="preserve">
+    <value>Red (Production)</value>
+  </data>
+  <data name="FrameColorYellow" xml:space="preserve">
+    <value>Yellow (Staging/UAT)</value>
+  </data>
+  <data name="FrameColorGreen" xml:space="preserve">
+    <value>Green (Test)</value>
+  </data>
+  <data name="FrameColorBlue" xml:space="preserve">
+    <value>Blue (Development)</value>
+  </data>
+  <data name="FrameColorPurple" xml:space="preserve">
+    <value>Purple (Custom)</value>
+  </data>
 </root>