Controls for windows and window coverings need to be easy to reach and manipulate. Controls (pull cords, wands, latches, etc) all need to be accessible in a low, easy-to-reach location for people to use, whether seated or standing. This means that window controls should be less than 48″ from the floor. Controls and latches also need to be able to be used without any requirement to use pinching, twisting, or grabbing motions.
Any items that block access to controls to open/close windows and coverings will create difficulty for some people. Furniture is typically the culprit here. There are even powered options to open and close window coverings with the touch of a switch on a remote or a smartphone.