If you DO get the Heki (and I agree it is a great concept, just poor execution), insist that they install the crank up or electric version.
The Heki midi comes in three versions: bar operated, crank operated, and electric motor operated. They share most of the same parts. I have only seen the bar operated here in the US in a camper. The bar mechanism (the track and latches in particular) are fragile and underspec'd, but the worst part about it is that the bar is above the bug screen. So to close it, you have to open the bug screen and let all the bugs in (actual trap them in, since you are closing the lid). This is madness, but typical of windows in Europe where they simply don't believe in bug screens.
The crank operated version has a crank to operate the lid, still underspec'd but maybe not as bad, and the crank is located inside the bug screen. You can close the lid, still trapping them but at least not letting them inside (let them out the next day if you like). Or tap the bug screen to get them airborne and you won't trap nearly as many as you close the lid. The electric version replaces the crank with an electric motor, I suppose that could be valuable to some but not to me.
I replaced the bar operated version with the crank version and I am one happy camper. Now if they would just upgrade all the components by about 2x it would be a good unit....
In theory you can order the parts to convert the bar to the crank version, though in practice it may be easier/cheaper to replace the whole thing.