Using slices (without parameters $width and $height) in a project theme can produce wrong png files

[contrerasmarc]

Hi, in my tests to use a common project theme for several apps, I detected an issue when you use slices in a css file.
When you use in the slice only $top and $left parameters, apparently Chance (SproutCore's CSS Framework) creates a anomalous png file (In Safari you arrive to see the buttons, but not in Firefox).
Then I added the parameters $width and $height the app works fine.
See the code (corrected) at https://github.com/contrerasmarc/my_project

I documented the issue at https://groups.google.com/forum/#!topic/sproutcore/vPU0GaMG7PQ

Regards

[mauritslamers]

Would it be possible to attach to this issue both the corrupt png as well as the correct one?