This is a small bug I've noticed. When I have selected a layer with turned off visibility and I use the ruler straighten command, a message appears saying: Error 8800: General Photoshop Error occurred. This functionality may not be available in this version of Photoshop. The command "Transform" is not currently available. Line: 217 -> layerRef.rotate( angle *180.0/Math.PI);
It should be swapped with a different message saying that you can't rotate a turned off layer.