backing store
When a server maintains the contents of a window, the off-screen saved pixels are known as a backing store.
before action
An action of a contact-display that is called when an event is dispatched to a contact, but before any other contact input processing is performed.
bit gravity
When a window is resized, the contents of the window are not necessarily discarded. It is possible to request the server to relocate the previous contents to some region of the window. This attraction of window contents for some location of a window is known as bit gravity.
A pixmap of depth one.
button grabbing
Buttons on the pointer can be passively grabbed by a client. When the button is pressed, the pointer is then actively grabbed by the client.
byte order
For image (pixmap/bitmap) data, byte order is defined by the server, and clients with different native byte ordering must swap bytes as necessary. For all other parts of the protocol, the byte order is defined by the client, and the server swaps bytes as necessary.