function getForm(formName)
{
  if (formName == undefined)
    formName = "form";

  var theForm = document.getElementById(formName);
  
  if (theForm == undefined)
    theForm = document.getElementsByName(formName)[0];
    
  return theForm;
}

function getFormField(fieldName, formName)
{
  var theForm = getForm(formName);
  
  if (theForm != undefined)
    return eval('theForm.' + fieldName);
}

function getFormValue(fieldName, defaultValue, formName)
{
  var field = getFormField(fieldName, formName);
  
  if (field != undefined)
    return field.value;
    
  return defaultValue;
}

function getFormIntValue(fieldName, defaultValue, formName)
{
  var field = getFormField(fieldName, formName);
  
  var intValue = defaultValue;
  
  if (field != undefined)
    intValue = parseInt(field.value);
  else
    return defaultValue;
    
  if (intValue == NaN)
    return defaultValue;
    
  return intValue;
}

function setFormValue(fieldName, value, formName)
{
  var field = getFormField(fieldName, formName);
  
  if (field != undefined)
    return field.value = value.toString();
}

function deselectTabs()
{
  var tab = document.getElementById('tab_w');
  if (tab)
    tab.style.backgroundImage = tab.style.backgroundImage.replace("w-s.gif","w-u.gif");
    
  tab = document.getElementById('tab_i');
  if (tab)
    tab.style.backgroundImage = tab.style.backgroundImage.replace("i-s.gif","i-u.gif");
    
  tab = document.getElementById('tab_n');
  if (tab)
    tab.style.backgroundImage = tab.style.backgroundImage.replace("n-s.gif","n-u.gif");
    
  tab = document.getElementById('tab_v');
  if (tab)
    tab.style.backgroundImage = tab.style.backgroundImage.replace("v-s.gif","v-u.gif");
}

function selectTab(mode)
{
  if (mode == undefined)
    mode = getFormValue('t', 'w', 'search');
  
  deselectTabs();
  
  var tab = document.getElementById('tab_' + mode);
  
  if (tab)
    tab.style.backgroundImage = tab.style.backgroundImage.replace("-u.gif","-s.gif");
}

function setSearchMode(mode)
{
  if (mode == undefined)
    mode = '';

  setFormValue('t', mode, 'search');
  
  selectTab(mode);
}

function setSearchString(searchString)
{
  if (searchString == undefined)
    searchString = '';
  
  setFormValue('q', searchString, 'search');
}

function clearCurrentPage()
{
  setFormValue('p', 1, 'search');
}