Altered widget from point function to match rendering order

Up to now, when widgets overlapped, the bottom most matched and received
mouse input. Now, the top most widget (the last one rendered, the last
one in the list) matches first, because the entire list of children is
searched before going down the tree (the last match is used).
Implemented horizontal scroll bar for frame widget
Modified the frame widget to adjust the horizontal scrollbar length

  - If the vertical scroll bar is not drawn, the horizontal scrollbar
    should use the entire frame width (it does now)
  - If the vertical scroll bar is drawn, the horizontal needs to be a
    little shorter for the button of the vertical scrollbar
  - Had to add a "set length" function to the scrollbar widget
Implemented frame buffer configuration for the subview widget