Quirks and workarounds

PyQt promoted widgets and py2exe

Avoid promoting widgets - this breaks themes.

If you absolutely promote a widget, make sure the subclass is imported somewhere. Py2exe appears to get rid of classes / modules that are not used anywhere, and that causes the Windows executable to fail to find them. You might need to mark the promoted class' include file as global in QtDesigner, too.

ui files

All .ui files use (or should use) one-space indents. Make sure whatever layout editor you use respects that, so you don't have to fix up commits caused by differing opinions on indents.