Thank you for your interest in the RadToolBar.
the current implementation of the RadToolBar does not respects the horizontal alignment. In order to stretch the tollbar you should place it inside a container (panel or grid) and initialize its HorizontalAlignment to Stretch.
About the toolbar's items positioning. All the items are stacked at the left side of the toolbar. As a workaround I suggest that you should use two toolbars placed inside a grid like in the attached example. Please give it a try.
However we planed to implement the alignment support for both the tollbar and its items. We hope this feature will be available soon after the Q2 release.
If you have any other questions about the RadToolBar please do not hesitate to contact us again.
the Telerik team