C# RichTextBox Format not shown if text loaded

I've got a RichTextBox in which I can format the text..

I can save the text as .txt and also load,

but when loaded, the formatting of the text is开发者_如何学JAVA "away"..

So what can I do, that the format stay?

Hope someone can help me..

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you have to use the RTF format: http://msdn.microsoft.com/en-us/library/8bf5hy2e(v=vs.80).aspx

TXT only saves the text but no formatting.