Is the Admin Menu z-index value high enough?

I've just come across an issue with the Leaflet module where a map zoom control has a CSS z-index value set to 1000, which is just slightly higher than the value accorded to the Admin Menu (999).

This renders above the menu, which is a sight annoyance and probably won't cause many problems for users. However, assuming that the Admin Menu is going to be the uppermost layer surely we could set the z-index value to higher than 999? Perhaps 9999 or even better 99999? That's a value browsers can handle and way above what any theme is likely to set for any element.

Thoughts?