1. X Window System is a low-level protocol
•Create/destroy windows
•Move/resize windows
•Map/unmap windows (show/hide windows)
•Receive user inputs (key presses/releases, mouse events)
•Draw lines/curves/bitmaps
2. Window Manager
•Controls the general appearance of windows and other graphical elements of the GUI.
•Chooses the size and position of windows, placing the decorative border around them, handling icons, handling mouse click outside windows (on the “background”) or on window-frame, handling certain keystrokes (e.g., Alt-F4).
3. Window
•Window information
Some basic attributes describing the window, Includes id, title, coordinates, map state, override redirect state, etc.
xwininfo
•Window properties
Extensible window attributes which heavily used by Window Manager
Can also used to inter-client communication
E.g., Icon, maximization state, coordinates hint, pid, etc.
xprop
4. Xevent
•An XEvent is data generated asynchronously by the X server as a result of
Some device activity
Side effects of a request sent by the X client
•Event Categories
Keyboard events: KeyPress, KeyRelease
Mouse events: ButtonPress, ButtonRelease, MotionNotify
Window crossing events: EnterNotify, LeaveNotify
Input focus events: FocusIn, FocusOut
Keymap state notification event: KeymapNotify
Exposure events: Expose, GraphicsExpose, NoExpose
Structure control events: CirculateRequest, ConfigureRequest, MapRequest, ResizeRequest
Window state notification events: CirculateNotify, ConfigureNotify, CreateNotify…
Colormap state notification event: ColormapNotify
Client communication events: ClientMessage, PropertyNotify, SelectionClear…