Disable textbox and not placed cursor in textbox.

function SetCheckBoxStatus() {

if (document.getElementById("<%=chkShow.ClientID%>").checked) {
document.getElementById("<%=txtArticleBody.ClientID%>").disabled = true;
document.getElementById("<%=fuThumbnailImage.ClientID%>").disabled = true;

}
else {
document.getElementById("<%=txtArticleBody.ClientID%>").disabled = false;
document.getElementById("<%=fuThumbnailImage.ClientID%>").disabled = false;

}
}