Hey there, this is for anyone else coming across this post.  This seems to work for me in version 10.2: (Just a note, that I had actually set the Caption Text to a default text value in the designer that I changed in the code below)

var

);

dialog._elements[1].innerHTML =

"PD Preferences";

Hi,

The header is accessible after dialog was initialized. For example, you may process ClientEvents.Initialize and implement it by something like below:

function initDialog1(dialog, evtArgs)
{
  dialog.get_header().setCaptionText('Client Caption');
}

You also may try to use internal member dialog._header, but while initialization it can be reset, so, your codes may have no effect or raise exception.

Have you found a solution for this? From what I have seen the function get_Header returns null if the dialogwindow is not in a "ready" or apparently "hidden" state.

I was able to change the header using this:

var webDialogWindow = $find('<%= webDialogWindow.ClientID %>');
webDialogWindow._header._props[0] = "My header";

I also tried the following:

var webDialogWindow = $find('<%= webDialogWindow.ClientID %>');
webDialogWindow.set_windowState(0x0);
webDialogWindow._header.setCaptionText("My Header");

http://forums.infragistics.com/forums/p/6584/27883.aspx

Setting the caption after showing the dialog also solves this problem:

var webDialogWindow = $find('<%= webDialogWindow.ClientID %>');
webDialogWindow.show();
webDialogWindow._header.setCaptionText("My Header");