white border in masthead

Hi experts,

I have customized the standard Tradeshow theme and assigned to a desktop.When i assigned that desktop to a user using rule collection a white color border kind og thing is getting displayed in masthead.

I guess its a kind of selection area i.e. it is pointing to the masthead selection soon after logging into the portal.

When any tab is pressed or mouse click it is disappearing

Any strategy to remove it?

Thanks

Deepak