Tiny little suggestion, but it's just something that's make sense I guess? Since I usually navigate to it through the event pop up, it took me a second to find it, and clicking on my voucher count with the currencies was my first instinct since some other sites take you to the bank or such if you click on your money.
Obviously it's in the shop menu but it'd be a nice little extra shortcut, eh?
Currently it just shows a little tooltip with the number [which, it would be handy if it said which even vouchers are too maybe] but it'd make sense since that's the only place they're ever used anyway.