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.(3) These occur as soon as a button is pressed. They are represented by lists that look exactly like click events (see section 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.
See section Motion Events.
Go to the first, previous, next, last section, table of contents.