Validates the client area of a Form within a rectangle by removing the rectangle from the update region of the specified window.
Form.Validate [left],[top],[width],[height]
Form.ValidateAll
left, top, width, height:Single exp
Validate is used to prevent redrawing of a rectangle. The upper left corner of the rectangle is given in left and top, the width in width and the height in height.
ValidateAll is used to prevent redrawing of the entire client-area rectangle.
Validate suppresses a redraw message aimed at a specific rectangle. Validate corresponds to the Windows function ValidateRect().ValidateAll corresponds to the Windows function ValidateRect( ,Null).
{Created by Sjouke Hamstra; Last updated: 12/05/14 by James Gaite}