I know 1.6 is 'old school', no worries. I'm aware there are some conversion issues between render window and the mouse coords if render window is resized.
Let's say I have an (invisible to the user) square/rectangular area within the screen, where if the user clicks within the area something happens. What is the best way to implement this so that, if a user resizes the screen, the area checking between both the square/rectangular area and the mouses coords is consistent regardless of how the window is resized? What SFML classes should I use for this?