Description
For an interactive interface where the user can add more plots, it seems impossible to use constrained_layout.
The whole adding a new axes is unnecesarily complex but it can be done. A new gridspec is set-up and the current axes are repositioned into their new "slots". This is working.
However the constrained_layout solver fails (error that height or width is 0).
Proposed Solution
It seems that some work has already been performed as part of setting a colorbar. It seems to me that with some effort it would be possible to extend that solution to be more generic.
Otherwise the whole layout boxes set-up could be exposed to the external API, such that the users can use it in a similar fashion.
(Ideally the matploplib API could make simpler adapating the gridspec after it has been created)
Additional context and prior art
None