Serious bugs in code folding: Code loss or crash when saving folded code

Using the code folding feature together with the "Clean Whitespace"-Option leads to different issues depending on OS used:
Windows 7 64bit: Crash or loss of code
Linux (Debian, Ubuntu, install with Qt SDK from nokia.com): Loss of code

How to reproduce:
Open a file (or create a new one) with some simple code, include a foldable block. Fold it and save the file (Ctrl-S) while the Clean Whitespace (and possibly also Clean Intendation) option is enabled. It seems to be better reproduceable, if there are some empty lines at the end of the block.

Result: On windows, frequent crashes (hangup or segfault) occur, or on both windows and linux all folded code or all but the last bracket is lost. I had no crash on linux so far

You can use the file attached to try it yourself - simply add two new lines after "return a.exec();", fold int main and press ctrl+s or save in any other way