WM_GETMINMAXINFO

  This message is sent to a window proc before a window is maximized, or
while a window is being resized or moved by dragging the mouse, This gives
the application the opportunity to alter the proposed dimensions of the
maximized or resized window.

Parameters
   wParam is not used.
   lParam is a far pointer to an array of five (5) RECT structures which
   contains the following
        r[0] is reserved
        r[1] is the maximum size of the window rectangle
        r[2] is reserved
        r[3] is the minimum tracking size of the window rectangle
        r[4] is the maximum tracking size of the window rectangle

Returns
  The window proc can alter the coordinates contained within any of the
passed RECTs if it wants to control the size and placement of the maximized
window, or if it wants to control the maximum or minimum tracking sizes.