Slow API responses highlight Wagtail's modal loading issues

[nimasmi]

Wagtail issue wagtail/wagtail#4006 points out that it's possible to open two modals in the Wagtail admin by quickly clicking the chooser button twice. With slow-responding APIs, this becomes more of a problem.

The solution is to add an inactive state to that button immediately when it is clicked, and possibly too to the list entries in the chooser, as choosing one for Wagtail Generic Chooser at least requires an API call to the 'get object' endpoint.

This issue remains in Wagtail's scope, but I think it's even more of a problem for projects implementing Wagtail Generic Choosers.