please help, an edit mode problem!!

I create my own controls in active-grid, like button, text..etc...
One control call lookup(one text + one button), it's used to open a modaldialog to choose you items, then put the data which you chosen into the text. The code is like this:

AW.UI.LookUp = AW.UI.ImageText.subclass();
AW.UI.LookUp.create = function(){

var obj = this.prototype;

obj.setAttribute("awx", "lookup");
obj.setClass("templates", "lookup");

obj.setClass("lookup", "box");

var button = new AW.HTML.TABLE;
button.setClass("lookup", "button");
button.setAttribute("cellspacing", "0");

button.setEvent("onclick", function(event){
//call function to showdialog to choose item
ClickMIBtn();

if(gEditData == "Invalidation")
{
gEditData = "";
}

this.setControlText(gEditData);

this.element().focus();
});

obj.setContent("box/sign", button);
obj.setContent("box/sign/html", "<tr class=\"aw-lk-1\"><td></td></tr><tr class=\"aw-lk-2\"><td>&nbsp;</td></tr><tr class=\"aw-lk-3\"><td></td></tr>");
};

When user leave the cell, I set the template as default(text) and call setCellText to put data into cells.

My problem is-If 1.I click the lookup-button to showdialog to get the data, it works fine, but when 2.I input data in text(never open dialog) and leave the cell, it doesn't trigger onCellSelectedChanged on first time, but trigger second time....

After trace the code, I find:
1. trigger onCellSelectedChanged and other function
2. just trigger onbeforedeactivate

It makes me confused!!, what is onbeforedeactivate mean?? Can somebody help .....

onbeforedeactivate is an IE event -

http://msdn.microsoft.com/en-us/library/ms536903(VS.85).aspx