/// <summary>
/// The gap at the top of the box (margin + border + pad) in layout pixels.
/// </summary>
internal int GapTrailing(LayoutTransform trans)
{
// Convert each separately to avoid rounding errors.
return(trans.MpToPixelsY(Style.Margins.TrailingMp)
+ trans.MpToBorderPixelsY(Style.Borders.TrailingMp)
+ trans.MpToPixelsY(Style.Pads.TrailingMp));
}