function initializeFilters() {

  // Bail early for Konqueror and IE5.2/Mac, which don't fully support dynamic

  // creation of form controls

  try {

    var test = document.createElement("input");

    test.type = "button";

    if (test.type != "button") throw Error();

  } catch (e) {

    return;

  }

  // Removes an existing row from the filters table

  function removeRow(button, propertyName) {

    var tr = getAncestorByTagName(button, "tr");

    var mode = null;

    var selects = tr.getElementsByTagName("select");

    for (var i = 0; i < selects.length; i++) {

      if (selects[i].name == propertyName + "_mode") {

        mode = selects[i];

        break;

      }

    }

    if (mode && (getAncestorByTagName(mode, "tr") == tr)) {

      // Check whether there are more 'or' rows for this filter

      var next = tr.nextSibling;

      if (next && (next.className == propertyName)) {

        function getChildElementAt(e, idx) {

          e = e.firstChild;

          var cur = 0;

          while (cur <= idx) {

            while (e && e.nodeType != 1) e = e.nextSibling;

            if (cur++ == idx) break;

            e = e.nextSibling;

          }

          return e;

        }

        var thisTh = getChildElementAt(tr, 0);

        var nextTh = getChildElementAt(next, 0);

        next.insertBefore(thisTh, nextTh);

        nextTh.colSpan = 1;

        thisTd = getChildElementAt(tr, 0);

        nextTd = getChildElementAt(next, 1);

        next.replaceChild(thisTd, nextTd);

      }

    }

    var tBody = tr.parentNode;

    tBody.deleteRow(tr.sectionRowIndex);

    if (!tBody.rows.length) {

        tBody.parentNode.removeChild(tBody);

    }

    if (propertyName) {

      var select = document.forms["query"].elements["add_filter"];

      for (var i = 0; i < select.options.length; i++) {

        var option = select.options[i];

        if (option.value == propertyName) option.disabled = false;

      }

    }

  }

  // Initializes a filter row, the 'input' parameter is the submit

  // button for removing the filter

  function initializeFilter(input) {

    var removeButton = document.createElement("input");

    removeButton.type = "button";

    removeButton.value = input.value;

    if (input.name.substr(0, 10) == "rm_filter_") {

      removeButton.onclick = function() {

        var endIndex = input.name.search(/_\d+$/);

        if (endIndex < 0) endIndex = input.name.length;

        removeRow(removeButton, input.name.substring(10, endIndex));

        return false;

      }

    } else {

      removeButton.onclick = function() {

        removeRow(removeButton);

        return false;

      }

    }

    input.parentNode.replaceChild(removeButton, input);

  }

  // Make the submit buttons for removing filters client-side triggers

  var filters = document.getElementById("filters");

  var inputs = filters.getElementsByTagName("input");

  for (var i = 0; i < inputs.length; i++) {

    var input = inputs[i];

    if (input.type == "submit" && input.name

     && input.name.match(/^rm_filter_/)) {

      initializeFilter(input);

    }

  }

  // Make the drop-down menu for adding a filter a client-side trigger

  var addButton = document.forms["query"].elements["add"];

  addButton.parentNode.removeChild(addButton);

  var select = document.getElementById("add_filter");

  select.onchange = function() {

    if (select.selectedIndex < 1) return;

    if (select.options[select.selectedIndex].disabled) {

      // Neither IE nor Safari supported disabled options at the time this was

      // written, so alert the user

      alert("A filter already exists for that property");

      return;

    }

    // Convenience function for creating a <label>

    function createLabel(text, htmlFor) {

      var label = document.createElement("label");

      if (text) label.appendChild(document.createTextNode(text));

      if (htmlFor) label.htmlFor = htmlFor;

      return label;

    }

    // Convenience function for creating an <input type="checkbox">

    function createCheckbox(name, value, id) {

      var input = document.createElement("input");

      input.type = "checkbox";

      if (name) input.name = name;

      if (value) input.value = value;

      if (id) input.id = id;

      return input;

    }

    // Convenience function for creating an <input type="radio">

    function createRadio(name, value, id) {

      var input = document.createElement("input");

      input.type = "radio";

      if (name) input.name = name;

      if (value) input.value = value;

      if (id) input.id = id;

      return input;

    }

    // Convenience function for creating a <select>

    function createSelect(name, options, optional) {

      var e = document.createElement("select");

      if (name) e.name = name;

      if (optional) e.options[0] = new Option();

      if (options) {

        for (var i = 0; i < options.length; i++) {

          var option;

          if (typeof(options[i]) == "object") {

            option = new Option(options[i].text, options[i].value);

          } else {

            option = new Option(options[i], options[i]);

          }

          e.options[e.options.length] = option;

        }

      }

      return e;

    }

    var propertyName = select.options[select.selectedIndex].value;

    var property = properties[propertyName];

    var table = document.getElementById("filters").getElementsByTagName("table")[0];

    var tr = document.createElement("tr");

    tr.className = propertyName;

    var alreadyPresent = false;

    for (var i = 0; i < table.rows.length; i++) {

      if (table.rows[i].className == propertyName) {

        var existingTBody = table.rows[i].parentNode;

        alreadyPresent = true;

        break;

      }

    }

    // Add the row header

    var th = document.createElement("th");

    th.scope = "row";

    if (!alreadyPresent) {

      th.appendChild(createLabel(property.label));

    } else {

      th.colSpan = 2;

      th.appendChild(createLabel("or"));

    }

    tr.appendChild(th);

    var td = document.createElement("td");

    if (property.type == "radio" || property.type == "checkbox") {

      td.colSpan = 2;

      td.className = "filter";

      if (property.type == "radio") {

        for (var i = 0; i < property.options.length; i++) {

          var option = property.options[i];

          td.appendChild(createCheckbox(propertyName, option,

            propertyName + "_" + option));

          td.appendChild(document.createTextNode(" "));

          td.appendChild(createLabel(option ? option : "none",

            propertyName + "_" + option));

        }

      } else {

        td.appendChild(createRadio(propertyName, "1", propertyName + "_on"));

        td.appendChild(document.createTextNode(" "));

        td.appendChild(createLabel("yes", propertyName + "_on"));

        td.appendChild(createRadio(propertyName, "!1", propertyName + "_off"));

        td.appendChild(document.createTextNode(" "));

        td.appendChild(createLabel("no", propertyName + "_off"));

      }

      tr.appendChild(td);

    } else {

      if (!alreadyPresent) {

        // Add the mode selector

        td.className = "mode";

        var modeSelect = createSelect(propertyName + "_mode",

                                      modes[property.type]);

        td.appendChild(modeSelect);

        tr.appendChild(td);

      }

      // Add the selector or text input for the actual filter value

      td = document.createElement("td");

      td.className = "filter";

      if (property.type == "select") {

        var element = createSelect(propertyName, property.options, true);

      } else if (property.type == "text") {

        var element = document.createElement("input");

        element.type = "text";

        element.name = propertyName;

        element.size = 42;

      }

      td.appendChild(element);

      element.focus();

      tr.appendChild(td);

    }

    // Add the add and remove buttons

    td = document.createElement("td");

    td.className = "actions";

    var removeButton = document.createElement("input");

    removeButton.type = "button";

    removeButton.value = "-";

    removeButton.onclick = function() { removeRow(removeButton, propertyName) };

    td.appendChild(removeButton);

    tr.appendChild(td);

    if (alreadyPresent) {

      existingTBody.appendChild(tr);

    } else {

      // Find the insertion point for the new row. We try to keep the filter rows

      // in the same order as the options in the 'Add filter' drop-down, because

      // that's the order they'll appear in when submitted.

      var insertionPoint = getAncestorByTagName(select, "tbody");

      outer: for (var i = select.selectedIndex + 1; i < select.options.length; i++) {

        for (var j = 0; j < table.tBodies.length; j++) {

          if (table.tBodies[j].rows[0].className == select.options[i].value) {

            insertionPoint = table.tBodies[j];

            break outer;

          }

        }

      }

      // Finally add the new row to the table

      var tbody = document.createElement("tbody");

      tbody.appendChild(tr);

      insertionPoint.parentNode.insertBefore(tbody, insertionPoint);

    }

    // Disable the add filter in the drop-down list

    if (property.type == "radio" || property.type == "checkbox") {

      select.options[select.selectedIndex].disabled = true;

    }

    select.selectedIndex = 0;

  }

}