This is directX9. When I render to a window, I make sure that the back buffer width and height are set to the same size as the window's client area and that works well. For fullscreen rendering until now I've been adjusting the window size to match the full screen size and removing the borders etc from the window, and then setting the back buffer's size to match. However by accident I've just found that if I don't bother to resize or alter the window in any way and just set the D3DPRESENT_PARAMETERS back buffer size to be the whole screen, and set the format to something suitable, and set the Windowed field to false then it all seems to work anyway even though the window isn't fullsceeen. Most guides I've read adjust the window parameters when going full screen but it seems to work fine for me without doing any of that. So should I be doing that or not?