Ask for passphrase once, but require confirmation each time a key is used?

[dalz]

The motivation is that I'd like to know when something wants to decrypt
a file. I could configure gpg-agent to not cache the key and ask for the
passphrase each time, but that is very annoying with a long passphrase,
so I was wondering if there was any other way to accomplish that.
What I'm thinking is a popup window that (while gpg-agent has the key)
replaces pinentry, requiring a simple click of a button to allow the
decryption. Is there any way to do this?

I'm pretty new to this, so feel free to point out that my idea is
pointless / makes no sense if that is the case!

--
dalz