I have solved the problem with the window pane! I remembered we have hundreds of disc boxes somewhere in the walk-in closet because we hold the discs in wallets. So I tried to choose the ones with the fewest scratch and cut them with my tablesaw. Then I could put the windows into their places. Some plaster work is necessery, I can see the sunlight coming through the gaps around the window frames. Although the sunlight is very poor, it's still rainy here!
I put wallpaper on the center parts of the wall. Certainly it's a little bit loose and dirty at the bottom. This room is in an old apartment house in Budapest. The house needs a serious renovating, but the panorama is magnificent!
I hung up the curtains, too. I'm too short, only 156 cm, so I had to use a ladder. I was ready to go out into my garden in rainfall to study our ladder, I'm very determined about miniatures! So it's old and rusty and spotted, like my real one.