Jean-Yves, I showed Bill Lyons a picture of the Erla Haube and he considered this a bird-cage canopy too. I guess he simply meant a canopy with framing over the top, opposed to the all-round vision bubbles of the American P-51 and P-47. The Dora canopy falls in the "bird-cage" category too I assume
Thanks for the additional info, by the way. Definitely not Gärtner then, that's clear...