Model Context Menu should have the enableBackwardTypeInference choice
Ptolemy II now supports backward type inference. The way this is enabled is that the top level container has a parameter called "enableBackwardTypeInference" that is set to true or false.
In Ptolemy II's Vergil, this is visible by right clicking on the background of the top level model.
This functionality is not present in the devel tree of Kepler.
The workaround is to drag in a Parameter, name it "enableBackgroundTypeInference" and set the value to true.