You can work around this using the 3rd party macro/scripting app called "Keyboard Maestro", from http://www.keyboardmaestro.com
Here's a screen shot of the simple script I use. Currently it only works when the App Store is in the background, and gets automatically activated by clicking a web link in Firefox or something, but you get the idea, this could be modified and improved in various ways.
Needless to say, security is compromised by storing your password in plain-text within Keyboard Maestro script, so be sure it's a unique, random password that you don't use anywhere else.
