I mean, Tcl/Tk has had this since the 90s. Rewrite your procs (functions) on the fly, delete GUI items on the fly, generate new events, create listeners on the fly, etc, etc.

Quite easy to create a GUI that's interactive AND a console you can script on at the same time to inspect / edit / change code.

For example, don't like your window attributes? Write code to destroy it, and re-create it and keep your "live" data unchanged, and it will redisplay in the new style / layout.

And sure, you could code up atomic transactions quite easily.

Itcl even lets you create / add /remove classes or specific class instances on the fly, or redefine class methods.