/// <summary>
    /// Reposition the tooltip so that it is within the bounds but not within
    /// the source
    /// </summary>
    public static void RepositionTooltip(RectTransform tooltip,
                                         RectTransform source,
                                         RectTransform bounds)
    {
        tooltip.position = source.position;

        // work in world space because it's easier
        var tooltipRect = tooltip.GetWorldRect();
        var sourceRect = source.GetWorldRect();
        var boundsRect = bounds.GetWorldRect();

        // divide the bounds into four overlapping rectangles on each side of
        // the source rect
        var xMinRect = Rect.MinMaxRect(boundsRect.xMin, boundsRect.yMin,
                                       sourceRect.xMin, boundsRect.yMax);
        var yMinRect = Rect.MinMaxRect(boundsRect.xMin, boundsRect.yMin,
                                       boundsRect.xMax, sourceRect.yMin);
        var xMaxRect = Rect.MinMaxRect(sourceRect.xMax, boundsRect.yMin,
                                       boundsRect.xMax, boundsRect.yMax);
        var yMaxRect = Rect.MinMaxRect(boundsRect.xMin, sourceRect.yMax,
                                       boundsRect.xMax, boundsRect.yMax);

        var rects = new[] { xMinRect, xMaxRect, yMinRect, yMaxRect };

        //  bounds                     bounds
        //+------------------------+ +--------+--------+------+
        //|                        | |        |        |      |
        //|                        | |        |        |      |
        //|          yMin          | |  xMin  |        | xMax |
        //|                        | |        |        |      |
        //|                        | |        |        |      |
        //+--------+--------+------+ |        +--------+      |
        //|        |        |      | |        |        |      |
        //|        | source |      | |        | source |      |
        //|        |        |      | |        |        |      |
        //+--------+--------+------+ |        +--------+      |
        //|          yMax          | |        |        |      |
        //|                        | |        |        |      |
        //+------------------------+ +--------+--------+------+

        // find the first division in which the tooltip rect will fit
        for (int i = 0; i < rects.Length; ++i)
        {
            Rect rect = rects[i];

            if (tooltipRect.width  <= rect.width
             && tooltipRect.height <= rect.height)
            {
                // push the tooltip rect into the division
                float pushR = Mathf.Max(0f, rect.xMin - tooltipRect.xMin);
                float pushU = Mathf.Max(0f, rect.yMin - tooltipRect.yMin);

                float pushL = Mathf.Min(0f, rect.xMax - tooltipRect.xMax);
                float pushD = Mathf.Min(0f, rect.yMax - tooltipRect.yMax);

                var push = new Vector2(pushL + pushR, pushU + pushD);

                tooltip.position += (Vector3) push;

                break;
            }
        }
    }