清理ColorPicker，进度条。修复UI问题

Melskin/Controls/SearchableComboBox.cs

@@ -13,8 +13,8 @@ namespace Melskin.Controls
     /// </summary>
     public class SearchableComboBox : ComboBox
     {
-        private TextBox _editableTextBox;
-        private bool _isInternalOperation;
+        private TextBox editableTextBox;
+        private bool isInternalOperation;
 
         static SearchableComboBox()
         {
@@ -41,30 +41,30 @@ namespace Melskin.Controls
 
         protected override void OnSelectionChanged(SelectionChangedEventArgs e)
         {
-            if (_isInternalOperation) return;
+            if (isInternalOperation) return;
 
-            _isInternalOperation = true;
+            isInternalOperation = true;
             base.OnSelectionChanged(e);
 
             // 重点 1：选中项改变后，必须彻底清空过滤器，否则下次打开下拉框只剩下一项
             this.Items.Filter = null;
-            _isInternalOperation = false;
+            isInternalOperation = false;
         }
 
         private void OnEditableTextBoxTextChanged(object sender, TextChangedEventArgs e)
         {
-            if (_isInternalOperation) return;
+            if (isInternalOperation) return;
 
-            string searchText = _editableTextBox.Text;
+            string searchText = editableTextBox.Text;
             string selectedText = GetItemDisplayText(SelectedItem);
 
             // 重点 2：断开锁定逻辑
             // 如果文本框的内容和当前选中项的文本不一致，说明用户正在打字替换内容
             if (SelectedItem != null && searchText != selectedText)
             {
-                _isInternalOperation = true;
+                isInternalOperation = true;
                 SelectedItem = null; // 必须将 SelectedItem 设为 null，否则 WPF 会强行还原文本
-                _isInternalOperation = false;
+                isInternalOperation = false;
             }
 
             // 重点 3：执行过滤
@@ -79,7 +79,7 @@ namespace Melskin.Controls
             };
 
             // 自动打开下拉框
-            if (!IsDropDownOpen && _editableTextBox.IsFocused && !string.IsNullOrEmpty(searchText))
+            if (!IsDropDownOpen && editableTextBox.IsFocused && !string.IsNullOrEmpty(searchText))
             {
                 IsDropDownOpen = true;
             }