This behavior is observed in DITA on FrameMaker 11.0.1.382 on Windows 7.
If I am editing a file that contains the <codeblock> element, make any change to that file in the XML View, and then save the file, FrameMaker adds 4 tab characters to the beginning of every line in the file and also deletes any leading spaces that exist inside <codeblock>. In effect, it is saving pretty printing from the XML View, corrupting my DITA source in the process. It does not matter whether I make the save in the XML View or return to WYSWIG View before doing so.
If the file does not contain a specialization of <pre>, no corruption occurs (evidenced by no proliferation of tab characters).
Please tell me I have missed a setting that would eliminate this problem.