Official comment
ou can do this by combining a pop-up ONTRAform with the ONTRApage!
Create an ONTRAform. Use the "Start from Scratch" option to start with a completely blank page and then add a Header Block. Configure the header block to suit; it will serve as your fixed header on your ONTRApage. Save the form.
On your ONTRApage, click the Settings tab, then select Pop Lightbox on User Scroll or Time on Page. Select your header ONTRAform for the pop up.
Use the following settings in that section:
Select Popup Position - Use the center top position.
When to Trigger Lightbox - Use "Display after 2 seconds"
All Other Settings - Leave blank or unchecked as shown here:
When published, the header will appear shortly after the page loads, and remain fixed at the top while you scroll the page. Note that the pop up ONTRAform used as the header will show a "X" to close the header as shown in this video: http://screencast.com/t/xNNjFvgyJw
