[texhax] TeX Gyre fonts problem with \textsl, \slshape

[P. P. Narayanaswami]

I am using MikTeX2.8. As suggested in the recent TUGBoat issue (pages 236 -240)
when I use
     \usepackage{tgpagella)  or \usepackage{tgtermes}
the Slant shape alone does not work with either \textsl  or \slshape.
Instead, if I use the old command \usepackage{mathpazo} 
\usepackage{mathptmx}, everything works fine. 
Is there something going wronmg here with slant shape?
How can one get slant shape with any of the Gyre fonts?

By the way, all other shpa change commands work fine with Gyre fonts.