#!/bin/bash

xev -event button | awk '
    BEGIN {
        e = 0;
        t = 0;
        c[0] = "33[31;1m"
        c[1] = "33[36;1m"
    }
    /Press/   {e = 0; printf "down "}
    /Release/ {e = 1; printf "up   "}
    /time/ {
        h = c[e];
        printf "%s", c[e]
        if (e) {
            printf "%8d %sn", ($6 - t), strftime("%M:%S")
        } else {
            printf "%8d %sn", ($6 - t), strftime("%M:%S")
        }
        t = $6 + 0
    }
'

In reality: 1 down
down      191 51:12
up         16 51:12
down       36 51:12

In reality: 1 down
down     1532 52:21
up         48 52:21
down       16 52:21

In reality: 1 down
down     1580 53:03
up         16 53:03
down       16 53:03
up       1189 53:04 (yes, held down button here as well)
down       18 53:04