Build parent-child relationship between "widgets".

Reimplemented painting to occur so that parent is painted first and then its children.

Signed-off-by: jhakonen <joyer83@gmail.com>
Handle events so that children will receive the event first and then its parent.

Signed-off-by: jhakonen <joyer83@gmail.com>
Added menu background which appears when ESC is pressed.

Signed-off-by: Janne Hakonen <joyer83@gmail.com>