FckEditor 如何设置输入文本的最大值验证？

如何在FckEditor中设置验证输入的最大值？
比如当输入字符超过16k时，提示已达到输入上线。

获取内容长度，然后根据长度判断
function GetLength()
{
// This functions shows that you can interact directly with the editor area
// DOM. In this way you have the freedom to do anything you want with it.

// Get the editor instance that we want to interact with.
var oEditor = FCKeditorAPI.GetInstance('FCKeditor1') ;

// Get the Editor Area DOM (Document object).
var oDOM = oEditor.EditorDocument ;

var iLength ;

// The are two diffent ways to get the text (without HTML markups).
// It is browser specific.

if ( document.all )     // If Internet Explorer.
{
    iLength = oDOM.body.innerText.length ;
}
else                    // If Gecko.
{
    var r = oDOM.createRange() ;
    r.selectNodeContents( oDOM.body ) ;
    iLength = r.toString().length ;
}

alert( 'Actual text length (without HTML markups): ' + iLength + ' characters' ) ;

}