FCK.InsertHtml() loses cursor position

I have several plugins that open in new dialog windows; because I require the 'application/xhtml+xml' mime type, I cannot use the built-in fckeditor dialog support. Previously, my dialogs were working fine, and the content they inserted into the editor appeared at the correct location.

With the 2.6.3 release, however, I've noticed that the content is always inserted at the beginning of the editor, no matter where the cursor is positioned when I invoke the dialog. This happens on every browser (IE, FF, etc.) on every operation system. The dialog does contain a form, and when a user enters information in this form, the original editor loses focus.

Here's a snippet of how I set up the editor (cribbed from the dialog tutorial):

var EquationEditorCommand=function(){};

EquationEditorCommand.prototype.Execute=function(){}

EquationEditorCommand.GetState=function() {
        return FCK_TRISTATE_OFF; 
}

EquationEditorCommand.Execute=function() {
        var url = '/ia/secure/popup/equation.action?fieldName=' + window.FCK.Name;
        // note: showPopUp creates an inline div, not a new browser window
        parent.showPopUp(url,500,358);
}

FCKCommands.RegisterCommand('Equation_Editor',EquationEditorCommand);

var oEquationEditorItem = new FCKToolbarButton('Equation_Editor', 'Enter a MathML Equation');
oEquationEditorItem.IconPath = FCKConfig.PluginsPath + 'equation/equation_icon.gif' ;
FCKToolbarItems.RegisterItem( 'Equation_Editor', oEquationEditorItem ) ;

When a button is clicked in my dialog, the following snippet is executed:

var FCK = FCKeditorAPI.GetInstance(fieldName);
var imageName = form.elements['embeddedImage.name'].value.split("&").join("&amp;").split("<").join("&lt;").split(">").join("&gt;");
FCK.InsertHtml('<img alt="image ' + imageID + '" id="' + imageID + '" src="/ia/image/' + imageID + '"/>');
hidePopUp();

Like I said, this used to work correctly. Has something changed recently, or alternatively, am I invoking the FCKEditor API incorrectly? Should I be doing something else to ensure that I preserve the cursor position? I'd appreciate any help!