set border_width to 6 px

otherwise Width and Height fields in Fill -> Bitmap will
be directly at the tab page border.

Also 12 px was too large on the left.

Change-Id: I4ae17020333d61bf80e02ea29989fbb4693da591
bring Tile and AutoFit back to the leven of Position

before ui-conversion both checkboxes were at the level of Position options.

Change-Id: Ie56937d64e657fba68ac8ffe44e5c42f2a576388
add missing border to GradientLB

Change-Id: I72651d514e2cf5abdce4a3323fa515426ff0438a