public static void SetSyntax(ICSharpCode.TextEditor.TextEditorControl editor, string fileName) { string syntax = "XML"; if (fileName.LastIndexOf('.') > 0) { string extension = fileName.Substring(fileName.LastIndexOf('.') + 1).ToUpper(); switch (extension) { case "BAS": case "VBS": case "VB": syntax = "VBNET"; break; case "CS": syntax = "C#"; break; case "CMD": case "BAT": syntax = "BAT"; break; case "C": case "RC": case "IDL": case "H": case "CPP": syntax = "C#"; break; default: break; } } editor.SetHighlighting(syntax); }