Server Resources

Complex data structures such as: windows, pixmaps, colourmaps, cursors, fonts and graphics contexts are stored in the server. They are known as server resources and clients reference them using an integer ID. For example, a client can request the server to create a window, and the server returns the window's ID to the client. Form then onwards, that ID is used as one of the parameters of any Xlib routine that requires access to that window.