// centre pos, autosized
public ImageElement AddTextCentred(Point poscentrehorz, Size max, string label, Font fnt, Color c, Color backcolour, float backscale, Object tag = null, string tiptext = null, StringFormat frmt = null)
{
ImageElement lab = new ImageElement();
lab.TextCentreAutoSize(poscentrehorz, max, label, fnt, c, backcolour, backscale, tag, tiptext, frmt);
Elements.Add(lab);
return(lab);
}