Maybe everybody knew this, but I finally sorted out how to get the panes out the the frames on these. 

The problem was getting the plastic frame split open to free the crazed acrylic pane.  I finally figured out that several laps around the seam with a matt knife does the trick. The exploded window frame shown below.

I need 4 more of these 4″ x 14″ ports if anyone has some to sell. Either color.