Info Catalog elisp: Drag Events elisp: Input Events elisp: Repeat Events

elisp: Button-Down Events

 
 20.7.6 Button-Down Events
 -------------------------
 
 Click and drag events happen when the user releases a mouse button.
 They cannot happen earlier, because there is no way to distinguish a
 click from a drag until the button is released.
 
    If you want to take action as soon as a button is pressed, you need
 to handle “button-down” events.(1)  These occur as soon as a button is
 pressed.  They are represented by lists that look exactly like click
 events (Click Events), except that the EVENT-TYPE symbol name
 contains the prefix ‘down-’.  The ‘down-’ prefix follows modifier key
 prefixes such as ‘C-’ and ‘M-’.
 
    The function ‘read-key-sequence’ ignores any button-down events that
 don’t have command bindings; therefore, the Emacs command loop ignores
 them too.  This means that you need not worry about defining button-down
 events unless you want them to do something.  The usual reason to define
 a button-down event is so that you can track mouse motion (by reading
 motion events) until the button is released.  Motion Events.
 
    ---------- Footnotes ----------
 
    (1) Button-down is the conservative antithesis of drag.
 

Info Catalog elisp: Drag Events elisp: Input Events elisp: Repeat Events