sf::VideoMode::getDesktopMode().width = 1920
window.getSize().x = 1400
Both are correct. I use github version of SFML, I think its max 2 days old.
What's more, even if I don't change window position, the window.getPosition().x is 1 and the window.getPosition().y is 26. (of course, the window is by default placed somewhere in the middle of screen, so they are wrong)