Hello all, I am working to make mplot3d feature-parity with regular axes objects. I have come across a possible design flaw with the CallbackRegistry. Many of the Axes3D methods are merely wrappers around Axes methods letting it do the work for x and y axis and then let Axes3D do the same for the z axis. In Axes.cla(), self.callbacks gets a CallbackRegistry of signals named "xlim_changed" and "ylim_changed". However, once that is set, it does not appear to be a way for me to add another signal of "zlim_changed" in Axes3D.cla(). I could replace self.callbacks with a new CallbackRegistry, but since there is a lot of interveaning code between that first initialization of self.callbacks and coming back out of Axes.cla(), I worry that some callbacks may have been registered by then and would get eliminated in the process. Is there a recommended way around this? Or maybe this is more evidence that we should move towards the use of a dictionary of axis objects and make Axes functions more agnostic to the number of axis? Thanks, Ben Root