For all I remember one must Zorder them on design time. (Layout Toolbar, "Bring to front", "Send to Back") The left most object is the one backmost, and the rest following from left to right. Do not miss separators.
You know, bring the leftmost to top, then the next to the right to the top and so on. This will sort them. Save.

Update:
This is the order you will see the objects top down on Properties Window or on Method-Editor Object-combo.
Possibly you need to close / reopen the toolbar class.

>calling ZOrder with 0 and 1 both had an effect but not the desired one unfortunately.
>
>>I have toolbar button that won't stay put (more than one actually).
>>since i am not able to control the "left" position at runtime, i am developing "Toolbar button phobia".
>>it is not a recognized mental disorder but that doesn't mean i am not crazy.
>>Does anyone know the cure?
>
>Wasn't that a problem of ZORDER? Just try zorder the elements.