Merge remote-tracking branch 'origin/master' into 1.12

# Conflicts:
#	Content/Shaders/GI/DDGI.flax
#	Content/Shaders/GUI.flax
#	Flax.flaxproj
#	Source/Editor/Windows/AboutDialog.cs
#	Source/Engine/Serialization/Stream.cpp
#	Source/Shaders/GUICommon.hlsl

Source/Editor/GUI/Input/ValueBox.cs

@@ -89,6 +89,11 @@ namespace FlaxEditor.GUI.Input
         /// </summary>
         public bool IsSliding => _isSliding;
 
+        /// <summary>
+        /// The color of the highlight to the left of the value box.
+        /// </summary>
+        public Color HighlightColor;
+
         /// <summary>
         /// Occurs when sliding starts.
         /// </summary>
@@ -211,6 +216,12 @@ namespace FlaxEditor.GUI.Input
                     Render2D.DrawRectangle(bounds, style.SelectionBorder);
                 }
             }
+
+            if (HighlightColor != Color.Transparent)
+            {
+                var highlightRect = new Rectangle(-3.0f, 0.0f, 3.0f, Height);
+                Render2D.FillRectangle(highlightRect, HighlightColor);
+            }
         }
 
         /// <inheritdoc />