I have put up several curtain poles above windows in my life. I even bought a heavy duty drill for those seemingly impenetrable concrete lintels.
However, after fitting 3 today in our new house with no problems, I began the fourth in my daughter's room which has a large dormer window. I began to drill above the middle of the window in the normal way, but the drill went straight through a thin veneer of plaster into what looks like plastic, only a few mils thick. Behind is a void.
Is there such a thing as a hollow plastic lintel? It seems to be the right place for the lintel in my amateur experience...
And if so, how should I be fixing the curtain pole brackets?