Looking for async I/O method between GUIs on Win32

[$Bill]

I have a GUI that I use to acquire URLs that point to web files.
I want to keep the GUI active while the file is being transferred to disk and I
have a second GUI that given a URL and disk path will handle the transfer.
I may wish to run multiple of the 2nd GUI (haven't decided yet), but want to allow
for it.
I need 1) a method to run the 2 or more tasks asynchronously, 2) a way to determine
the return status to the 1st GUI. There are a number of ways I could do this, but
I'm looking for something that will blend into the event driven GUI mechanism.

Back in my mini-computer days, I would have forked off the 2nd GUI and used a shared
memory region to pass the status back on completion and a semaphore to handle any
simultaneous memory access. But digging into Win32 internals from Perl complicates
things a bit. Has anyone got an elegant solution to this besides just forking off
a process and polling a pipe/file to wait for the response or using a socket to
communicate (seems overly complicated) status back. I also was thinking about using
threads in a single task (not sure how GUI events fit into threads).

So any elegant suggestions on the high level method of GUI communication between two
GUI tasks would be appreciated - hopefully someone who has done it successfully. ;)

PS: I'm using regular Perl Tk for the GUI.

TIA, Bill

[star mister]

Perhaps the module Promises could be a good option:

https://metacpan.org/pod/Promises

Their example looks somewhat like what you hope to do.
You would also need modules AnyEvent::HTTP and JSON::XS

And there is running parallel operations with fork:

https://metacpan.org/pod/Parallel::ForkManager

Tk has an event loop you can tie into if the above seems complex:

https://tkdocs.com/tutorial/eventloop.html

https://www.foo.be/docs/tpj/issues/vol1_3/tpj0103-0006.html