The short 'strip', near the front edge on top of the canopy, was a 'piano' hinge, which allowed the canopy to flex when slid back, as the runners kept the bottom frame of the canopy close to the fuselage. Behind this, almost in the centre of the canopy, is the small, triangular 'hump'. This was the fairlead opening for the pulley that held the radio antenna wire under tension. The outline of the latter should be painted. The 'hinge' may well have been coated metal, with the plexiglass/Perspex visible, but looks dark in photos, so it is acceptable to paint this. About two weeks ago, Wojtek posted some excellent drawings/diagrams, showing the arrangement of these, and the construction of this canopy and it's runner system, as well as the 'blown' hood. Problem is, I can't remember which thread it was in!!
I think the set-up is visible in the pics of my Dora, and might just show the internal end of the antenna wire, running back under the canopy.