UIScrollbar width

I have a ScrollPane with two textfields and UIScrollbars. I set the dimensions so that everything fits in the ScrollPane width-wise perfectly (i.e. without the horizontal scroll bar appearing).

However, the horizontal scroll bar does appear. When I scroll to the right, there is nothing additional there. If I remove the UIScrollbars, the bar disappears, so theres the root. If I trace the objects under the mouse in that empty space I get:
>> instance357 : [object Shape]
>> instance359 : [object Shape]
>> instance358 : [object MovieClip]
>> instance355 : [object ScrollPane_upSkin]
>> instance184 : [object ScrollPane]
The two scrollpane objects I understand. The MovieClip I am pretty sure is a part of the upSkin since it shows up everywhere the upSkin shows up. The two shapes are what I think is at issue here.

My assumption is that there is a non-visible component of the UIScrollbar that is inside the container Sprite. Based on what I know of the UIScrollBar’s components, I am thinking it is the focus Rectangle, but I have no idea if that’s accurate or how to test it. All I know is whatever is causing the problem appears to be exactly 100 pixels wide.

If this sounds accurate, does anyone have any idea what’s going on or how to fix it, or even how to further tease out what is the problem? If not, is there a way to set a maximum width of a Sprite or remove the horizontal scroll bar of a scrollpane? If not, is there any other creative means to get rid of my horizontal scroll bar?