Visual Studio中的哪个设置将我保存的文件标记为脏

Many times when I just open a file in VS, it shows as changed in its TFS and if I do a compare with latest version, it shows nothing which is correct. What is it that it is changing upon opening and saving a file? ( both .XAML and .cs files) that marks them as dirty? So I can disable it Many times when I just open a file in VS, it sh