Variable: track-mouse
track-mouse is a variable defined in keyboard.c.
Value
nil
Documentation
Non-nil means generate motion events for mouse motion.
The special values dragging and dropping assert that the mouse
cursor retains its appearance during mouse motion. Any non-nil value
but dropping or drag-source asserts that motion events always
relate to the frame where the mouse movement started. The value
dropping asserts that motion events relate to the frame where the
mouse cursor is seen when generating the event. If there's no such
frame, such motion events relate to the frame where the mouse movement
started. The value drag-source is like dropping, but the
posn-window will be nil in mouse position lists inside mouse
movement events if there is no frame directly visible underneath the
mouse pointer.
Probably introduced at or before Emacs version 25.1.
Source Code
// Defined in /usr/src/emacs/src/keyboard.c
DEFVAR_LISP ("track-mouse", track_mouse,
doc: /* Non-nil means generate motion events for mouse motion.
The special values `dragging' and `dropping' assert that the mouse
cursor retains its appearance during mouse motion. Any non-nil value
but `dropping' or `drag-source' asserts that motion events always
relate to the frame where the mouse movement started. The value
`dropping' asserts that motion events relate to the frame where the
mouse cursor is seen when generating the event. If there's no such
frame, such motion events relate to the frame where the mouse movement
started. The value `drag-source' is like `dropping', but the
`posn-window' will be nil in mouse position lists inside mouse
movement events if there is no frame directly visible underneath the
mouse pointer. */);