Here is the code to maintain value of FckEditor value during postbacks,

 

Write in Page_Load event,

 

Page.ClientScript.RegisterOnSubmitStatement(

fckContentPage.GetType(),

“fckContentPage”,

“FCKeditorAPI.GetInstance(‘” + fckContentPage.ClientID + “‘).UpdateLinkedField();”);

 

Here fckContentPage is ID of FckEditor