Inactive button state

There doesn't seem to be a differentiation between normal buttons and inactive buttons in this theme...
For example: in the Views interface, the main Save button becomes inactive when editing something (like the Empty Text for example). This theme, however, makes it still look like a normal button, so it's a bit confusing when you're trying to click on it and it does nothing (this isn't helped by the fact that hovering over the button makes it change backgrounds like other normal, clickable buttons). I think inactive buttons should be semi-transparent and/or not hoverable.

The attached screenshot shows the difference between Garland and this theme (though it's had to tell the difference without being able to hover over them and see the change).