A window's position is defined as the x,y coordinates of its lower-left corner. These coordinates, sometimes called window coordinates, always are relative to the lower-left corner of the parent window. For example, a window having the coordinates (10,10) is placed 10 pels to the right of, and 10 pels up from, the lower-left corner of its parent window. Notice, however, that a window can be positioned anywhere in relation to its parent, but always relative to the parent's lower-left corner.

Adjusting a window's position can improve drawing performance. For example, an application could position a window so that its horizontal position is a multiple of 8, relative to the screen origin (the lower-left corner of the screen). Coordinates that are multiples of 8 correspond to byte boundaries in the screen-memory bit map. It is usually faster to start drawing at a byte boundary.

By default, the system positions a frame window on a byte boundary; but an application can override this action by using the FCF_NOBYTEALIGN style when creating the window.