When writing a new Display Format for a given type using the debug helpers, we are obliged to write the qform__MyType() function for all the possible typedefs of the type.
This is very unpractical in situations where your type is a templated class with lots of templates and typedefs are often used (e.g. when working with the Eigen library).

In order to reproduce this problem, try both the qttypes.py that I attach below, with the sample project attached. Notice you will need the Eigen library installed.

With "qttypes.py" where all the qform__MyTypedef() are present: when you debug the Gnuplot Display Format is available and working for VectorXf, MatrixXf,...

With "qttypes_withouttypedefsqform.py" where all the qform__MyTypedef() are commented out: when you debug the Gnuplot Display Format is not available for VectorXf, MatrixXf,...