MATLAB: Are some of the blocks in the model light grey instead of black in Simulink 6.6 (R2007a)

Question

Some blocks and the signals they drive are colored light grey instead of black although I did not use the "Sample time colors" functionality. In past releases the blocks were rendered black for the same model file.

Answer 1

In order to avoid having white blocks on white background Simulink modifies the color of these blocks to make them visible.

In and before Simulink 6.5 (R2006b) these blocks were rendered black, so it looked they have the default color. You may have not even noticed that the color for your blocks was set to the background color.

As of Simulink 6.6 (R2007a) blocks that have the same color as the background, e.g. white are rendered light grey.