A visual of CopyFrom- Parent means the visual type is taken from the parent. Specify the width and height, which are the created window's inside dimensions and do not include the created window's borders. Specify the x and y coordinates, which are the top-left outside corner of the window's borders and are relative to the inside of the parent window's borders. The XCreateWindow function creates an unmapped subwindow for a specified parent window, returns the window ID of the created window, and causes the X server to generate a CreateNotify event. The created window is placed on top in the stacking order with respect to siblings.
Coordinates are integral, in terms of pixels, and coincide with pixel centers.
Each window and pixmap has its own coordinate system. For a window, the origin is inside the border at the inside, upper-left corner. For class InputOutput, the visual type and depth must be a combination supported for the screen, or a BadMatch error results. The depth need not be the same as the parent, but the parent must not be a window of class InputOnly, or a BadMatch error results. If either condition is not met, a BadMatch error results.