Is there a way to connect the notebook front end to both kernels, 11.3 and 12.0 at the same time. So I can run certain commands in older version.
It would be nice to have a way to run certain cells in specified kernel, i.e. lock the cells to certain kernel so they always evaluate in the specified kernel.
Also a way to move all current definitions from one kernel to the other one instantly without evaluating the commands again one by one in the other kernel. (Basically copy the current state of one kernel and paste it on the other one)
Note: I know the front-end servicing kernel will remain to be the version of the notebook but if there is a way to change the front-end servicing kernel as well that would be nice.