Patching the Button class this way is something I don’t normally think of, coming from a C++ background. Thanks!
And I could revert to the decorator approach if my app needs finer control. With some links/buttons, for example, it might suffice simply to disable the control until the handler returns.
Edit: Luckily, this problem has reared its head in only one spot in my code, so I was able to keep the scope of the change very small. But I’ll keep this tactic on hand, for worse cases.