- Use QGridLayout for setting up View layout

- Added QSpacerItems in order to properly implement frame around edition area.
- properly account for whether style requires frame around contents only, or around contents + scrollbars
- Call style primitive in order to render a frame around the said area, with proper mouse-over and focus set.
- Adjust scrollbar background based on whether frame must be drawn around contents only, or scrollbars+contents
- Force update of widget and scrollbars on focusIn and focusOut events

CCBUG: 158379
REVIEW: 120147