In order not to have the taskbar drawn on top of the game window, i set the resolution in the app : 3440x1440
But it's as I had put the double or so. I get fullscreen without taskbar alright, but I see just a part of the game.
Step by step I found out I had to put this resolution in order to get the full image : 2293x959
But with this resolution I get the taskbar in top of the game :(

Edit : I've just found out the problem : i use a 150% DPI
Maybe you could take into account the system DPI? In order for the user to be able to enter the true resolution