I would like to switch admin themes from a core theme (seven) to a custom sub-theme so I can add some customization without hacking core.
When I install the new sub-theme it creates all the block placement settings and leaves them header or content. I haven't changed any regions between the two themes, and just want to copy all the blocks from the seven theme to the current theme. I know I can check block settings with block plugin manager (
plugin.manager.block) but I don't know what blocks to edit. I would like to know how to get a list of all the blocks from the old theme and copy all the placement to new theme programmatically.