如何改变语法突出显示颜色的Avalon编辑(WPF)？

// 创建语法规则
var keywordRule = new RegexRule("KeywordRule", @"\b(while|if|else)\b", RegexOptions.Compiled | RegexOptions.Singleline);
var commentRule = new RegexRule("CommentRule", @"//.*$", RegexOptions.Compiled | RegexOptions.Singleline);
var stringRule = new RegexRule("StringRule", @"""([^""\\]|\\.)*""", RegexOptions.Compiled | RegexOptions.Singleline);

// 定义颜色样式
var keywordStyle = new TextStyle(Brushes.Blue);
var commentStyle = new TextStyle(Brushes.Green);
var stringStyle = new TextStyle(Brushes.Red);

// 应用样式到编辑器
editor.SyntaxHighlighting = new CustomHighlightingDefinition(keywordRule, commentRule, stringRule);
editor.SyntaxHighlighting.Styles.Add(keywordRule, keywordStyle);
editor.SyntaxHighlighting.Styles.Add(commentRule, commentStyle);
editor.SyntaxHighlighting.Styles.Add(stringRule, stringStyle);