If the user presses and releases the left mouse button over the same location, that generates a sequence of events like this:
(down-mouse-1 (#<window 18 on NEWS> 2613 (0 . 38) -864320)) (mouse-1 (#<window 18 on NEWS> 2613 (0 . 38) -864180))
While holding the control key down, the user might hold down the second mouse button, and drag the mouse from one line to the next. That produces two events, as shown here:
(C-down-mouse-2 (#<window 18 on NEWS> 3440 (0 . 27) -731219))
(C-drag-mouse-2 (#<window 18 on NEWS> 3440 (0 . 27) -731219)
(#<window 18 on NEWS> 3510 (0 . 28) -729648))
While holding down the meta and shift keys, the user might press the second mouse button on the window’s mode line, and then drag the mouse into another window. That produces a pair of events like these:
(M-S-down-mouse-2 (#<window 18 on NEWS> mode-line (33 . 31) -457844))
(M-S-drag-mouse-2 (#<window 18 on NEWS> mode-line (33 . 31) -457844)
(#<window 20 on carlton-sanskrit.tex> 161 (33 . 3)
-453816))
The frame with input focus might not take up the entire screen, and
the user might move the mouse outside the scope of the frame. Inside
the track-mouse macro, that produces an event like this:
(mouse-movement (#<frame *ielm* 0x102849a30> nil (563 . 205) 532301936))