What is the point of this?
At first, fast iteration on the UI.
Right now I'm about even on the time spent on a failed attempt to make 'Supplies Ok' combobox (NewManufactureListState::_cbxFilter) not reset the 'Category' combobox (NewManufactureListState::_cbxCategory) versus the whole of this embedding work. And I don't like much more in the UI than one pitiful misbehaving combobox (all I got for the time wasted is the understanding that it just can't be done with two comboboxes, phew).
This approach doesn't requre recompile after every teeny tiny change, and in a couple of hours won't even require restarting the game for any changes to apply, which means I won't have to waste time staring at the linker having changed a couple of characters in a text string.
The python api is being kept as close to the c++ one as reasonable, so if someone feels like porting anything back, it shouldn't become a total rewrite.