Resolution problem

I'm playing the tiny bang story on Steam, on a gpd win windows 10 computer. The screen resolution is 1280x720. It seems that on every screen I can't see the bottom edge. I think the windows are 768 tall. This means that on level 1 there's a puzzle piece I can't get to.
When I try to switch to windowed mode, I get a popup saying that it can't switch to windowed mode.
Is there any way I can change the resolution of the game, or drag the window to see the bottom part?

Thanks!