A tampermonkey script to be able to track multiple hours at once in mantis.

tamper-mantis.js

// ==UserScript==
// @name         Mantis ajax
// @namespace    http://your.homepage/
// @version      0.1
// @description  enter something useful
// @author       You
// @match        http://mantis.virtualmindsoftware.com/view.php?id=15640#timerecord
// ==/UserScript==

/* To track hours, you do this:
1) Navigate to any mantis issue/bug
2) Run the following

Definition for t_ is : t_(day, hour, hours, information[, bug_id, year])
For example:

_mantisAjaxArray([
  _t(1, 8, '02:00', 'I did nothing today', 335),
  _t(3, 8, '06:00', 'I did more today', 366)
])

In that example, I loaded 2 hours for the 1st of August with the label 'I did nothing today', for the bug with id 335.
And 6 hours for the 3rd of august with the label 'I did more today', for the bug with id 336.
The id of a bug is found in the url: "/view.php?id=16306".

The hours are loaded sequentially since each request needs a token for its own.
*/

function _mantisAjaxArray(arr) {
    var length = arr.length;
    var current = (s_(arr[0])());
    for (var i = 1; i < length; i++) {
        current = current.then(s_(arr[i]));
    }
}

function t_(day, month, hours, information, bug_id, year) {
    if (!bug_id) bug_id = $("[name='bug_id'][type='hidden']").val();
    if (!year) year = new Date().getFullYear();
    return {
        bug_id: bug_id,
        day: day,
        month: month,
        year: year,
        time_value: hours,
        time_info: information,
        Add: 'Add'
    }
}

function s_(data) {
    return function() { 
        var token = $("[name='plugin_TimeTracking_add_record_token']").val();
        data["plugin_TimeTracking_add_record_token"] = token;
        return $.post('http://mantis.virtualmindsoftware.com/plugin.php?page=TimeTracking/add_record', data)
        .then(function(res) { 
            console.log(data);
            var token = $(res).find("[name='plugin_TimeTracking_add_record_token']").val();
            $("[name='plugin_TimeTracking_add_record_token']").val(token);
        })
        .fail(function(res) { console.error(res); })
    }
}

if (unsafeWindow.s_ == undefined) {
   unsafeWindow.s_ = s_;
   unsafeWindow.t_ = t_;
   unsafeWindow._mantisAjaxArray = _mantisAjaxArray;
}