Random order of XML attributes when saving

[mgunyho]

If I open a syncdata file and save it, the attributes in the XML row, value and interpolation are shuffled each time, and git thinks all keys in the file have been rewritten. This makes merging files a headache. Apparently, this is caused by QDomElement.setAttribute (here) storing the keys in a hashmap, which shuffles the keys on purpose (see here). This could be fixed by seeding the hash as suggested in the SO thread.

[kusma]

Hmm, interesting. I haven't seen this behavior myself, so I wonder if this is dependent on Qt versions... I also wasn't aware that QtXML is deprecated, which I think is a strong argument to rewrite the code to use QXmlStreamReader/QXmlStreamWriter instead... I think the old Qt4 support can be binned anyway.

[kusma]

This behavior started in Qt5.6. The automated windows build (which is what I use) use Qt5.5. This explains why I haven't seen this behavior.

Thanks for reporting. I think a quick fix should be easy to do, like you suggest.

[kusma]

Hmm, I just tried to reproduce this on Qt 5.11 on Ubuntu, and I seem to get consistent behavior...

@mgunyho: What environment do you trigger this under?

[kusma]

OK, never mind. I managed to trigger it after some more tries. I had to restart the editor in between, I guess the hash stays constant.

[kusma]

@mgunyho: OK, could you check if #74 fixes the issue for you?

[mgunyho]

Seems to work, thanks!