sandbox NOT EMPTY indicator

[bobik]

In windows GUI there should be some indicator showing that particular sandbox is not empty. For instance slightly different icon. When I want to empty sandboxes I do not remember which ones were used and I click on every one, only to see on half of them, that they are empty already. This is unnecessarily annoying.

[Craig@Invincea]

You would end up having a lot of icons if you want one per SB.