ToolstripButtons in IE do not show border.

Observable in: SmartClient Version: v9.1p_2014-05-28/Pro Deployment (built 2014-05-28) and up

Browser: IE 11 and possibly lower

Issue:
The border for buttons in the Toolstrip does not show or will show but then disappears.

Steps to reproduce:
In the feature explorer for Toolstrip (http://www.smartclient.com/docs/9.1/a/system/reference/SmartClient_Explorer.html#toolstrip) in IE.

Set the border property for one of the toolstripbuttons and try it.

Then hover over the button with the border.

Result:
The border appears to disappear.

Question:
Is this an expected behavior or an issue that is only prevalent in the feature explorer (for we are having a similar issue with our own app)?