MotionNotify

MotionNotify is an event in the X Window System that is generated when the pointer (mouse) moves. This event is crucial for graphical user interfaces, allowing applications to track the cursor's position and react accordingly. When the pointer moves within a window's boundaries, the X server typically sends a MotionNotify event to that window.

Applications can choose to select for MotionNotify events. When selected, the window manager or application will receive these events and can then use the provided coordinates to update its display, highlight elements under the pointer, or perform other actions. The frequency of MotionNotify events can be configured, with options to receive events for every pointer movement or at a reduced rate to conserve resources. This configuration is often managed through the X server's settings or specific application preferences.

Understanding MotionNotify events is fundamental for developers working with X11 applications that require interactive graphical elements or precise pointer tracking. It forms the basis for many common user interactions, from simple cursor visibility to complex drag-and-drop functionalities.