创建CheckBox样式的下拉列表

/*
  Checkbox style Multi-Select Picklist
  author: Jim Wang @ January 2009
  http://jianwang.blogspot.com
  http://mscrm.cn
*/

// PL - the picklist attribute; PLV - used to save selected picklist values 
var PL = crmForm.all.new_picklist;
var PLV = crmForm.all.new_picklistvalue;

if( PL != null && PLV != null )
{
  PL.style.display = "none";
  PLV.style.display = "none";
  
  // Create a DIV container 
  var addDiv = document.createElement("<div style='overflow-y:auto; height:80px;border: 1px #6699cc solid;background-color: #ffffff;' />");
  PL.parentNode.appendChild(addDiv);
  
  // Initialise checkbox controls
  for( var i = 1; i < PL.options.length; i++ )  
  { 
    var pOption = PL.options[i];
    if( !IsChecked( pOption.text ) )
      var addInput = document.createElement("<input type='checkbox' style='border:none; 25px; align:left;' />" );
    else
      var addInput = document.createElement("<input type='checkbox' checked='checked' style='border:none; 25px; align:left;' / >" );
  
    var addLabel = document.createElement( "<label />");
    addLabel.innerText = pOption.text;
  
    var addBr = document.createElement( "<br />");
  
    PL.nextSibling.appendChild(addInput);
    PL.nextSibling.appendChild(addLabel);
    PL.nextSibling.appendChild(addBr);
  }
  
  // Check if it is selected
  function IsChecked( pText )
  {
    if(PLV.value != "")
    {
      var PLVT = PLV.value.split("||");
      for( var i = 0; i < PLVT.length; i++ )  
      { 
        if( PLVT[i] == pText )
          return true;
      }  
    }
    return false;
  }
  
  // Save the selected text, this filed can also be used in Advanced Find
  crmForm.attachEvent( "onsave" , OnSave);
  function OnSave()
  {
    PLV.value = "";
    var getInput = PL.nextSibling.getElementsByTagName("input");
  
    for( var i = 0; i < getInput.length; i++ )  
    {   
      if( getInput[i].checked)
      {
        PLV.value += getInput[i].nextSibling.innerText + "||";
      }
    }  
  } 
}

其中div 的style必须指定 'overflow-y:auto;‘

参考：http://www.cnblogs.com/MSCRM/articles/1377386.html