优化，改bug

Signed-off-by: TRADER_FOER <lhf190@outlook.com>

Assets/Scripts/DynamicUI/Hierarchy/HierarchyTab.cs

@@ -55,6 +55,10 @@ namespace Ichni.Editor
             targetElement.connectedTab = this;
             this.isExpanded = false;
             this.isSelected = false;
+            if (BgImage != null)
+            {
+                BgImage.color = new Color(0.5f, 0.5f, 0.5f, 0);
+            }
             this.childTabList = new List<HierarchyTab>();
 
             // 清除旧的缩进线
@@ -453,4 +457,4 @@ namespace Ichni.Editor
 
         }
     }
-}
+}