How to get the URL of a Gmail or other webapp page in Chrome "application shortcut" mode?

The best way to do it is this little workaround:

Right click with your mouse inside the visble area of the web-page somehwhere. A context menu should appear, select "view page source".

Alternativeley just type ctrl-u.

A completely new browser tab will open and in the address bar of this new tab you can see the URL that you are looking for. Just omit the first part of it which says view-source: and copy the remainder to the clipboard for further processing. Don't forget to close that tab, it is no longer necessary.

Unfortunateley the "Copy URL" entry in the system menu has gone away in new versions of google chrome.

Ok, I found the right answer: Click the system menu (top left hand corner). Select "Copy URL".