combobox.style:=csOwnerDrawFixed;
procedure TForm1.ComboBox1DrawItem(Control: TWinControl; Index: Integer; Rect: TRect; State: TOwnerDrawState);
begin
if ComboBox1.DroppedDown then
begin
StretchBlt(ComboBox1.Canvas.Handle,Rect.Left,Rect.Top,Rect.Right-Rect.Left,Rect.Bottom-Rect.Top,Image1.Canvas.Handle,Rect.Left,Rect.Top,Rect.Right-Rect.Left,Rect.Bottom-Rect.Top, cmSrcCopy);
// ComboBox1.Canvas.CopyRect(Rect,Image1.Canvas,Rect);
ComboBox1.Canvas.Brush.Style:=bsClear;
ComboBox1.Canvas.TextOut(Rect.Left + 2, Rect.Top, ComboBox1.Items[Index]);
end
else
begin
ComboBox1.Canvas.TextOut(Rect.Left + 2, Rect.Top, ComboBox1.Items[Index]);
end;
end;