Code:

uses

RichEdit;

procedure RE_SetSelBgColor(RichEdit: TRichEdit; AColor: TColor);

var

Format: CHARFORMAT2;

begin

FillChar(Format, SizeOf(Format), 0);

with Format do

begin

   cbSize := SizeOf(Format);

   dwMask := CFM_BACKCOLOR;

   crBackColor := AColor;

   Richedit.Perform(EM_SETCHARFORMAT, SCF_SELECTION, Longint(@Format));

end;

end;

// Example: Set clYellow background color for the selected text.

procedure TForm1.Button1Click(Sender: TObject);

begin

RE_SetSelBgColor(RichEdit1, clYellow);

end;