Hi Melchior,
Thank you for your patch!
Your patch uses the UTF-8 character set which is not what Wine's (or the native) resource compiler expects.
If the source file on your disk uses UTF-8 (check with 'file source.rc') you can fix this by converting it to an acceptable character set, for example like this:
$ iconv --from-code UTF-8 --to-code CP1252 source.rc > source.CP1252.rc
It could also be that your mail client converts the patch to UTF-8. In this case you should check your settings. It may also help to attach the patch instead of sending it inline if you were not doing that already.
I also saw this:
+ PUSHBUTTON "Alle Improtieren",IDC_IMPORTALL,7,252,52,14
-Hans