[scotty]

Create the extra buttons before you create the dialog, with something like this:

myzimlet.prototype.setupDialog = 
function() {
    var infoButtonId = Dwt.getNextId();
    this._infoButton = new DwtDialog_ButtonDescriptor(infoButtonId, "More Info");
    var chpassButtonId = Dwt.getNextId();
    this._chpassButton = new DwtDialog_ButtonDescriptor(chpassButtonId, "Change Password");

    this._dlg = new DwtDialog({parent: ..., title: '...', standardButtons: [DwtDialog.DISMISS_BUTTON], extraButtons: [this._infoButton, this._chpassButton]});

    this._dlg.setButtonListener(infoButtonId, new AjxListener(this, this.dlgButtonHandler, "info"));
    this._dlg.setButtonListener(chpassButtonId, new AjxListener(this, this.dlgButtonHandler, "chpass"));
    this._dlg.setButtonListener(chpassButtonId, new AjxListener(this, this.dlgButtonHandler, ""));
};

myzimlet.prototype.dlgButtonHandler = 
function(action) {
    this._dlg.popdown();
    this._dlg.dispose();
    switch (action) {
        case "info":
            window.open(infoURL, "More Info");
            break;
        case "chpass":
            window.open(chpassURL, "Change Password");
            break;
    }
};