Try setting Enabled = false and also handling PrepareViewStyleInfo on the embedded grid to see if that gives you what you want.
this.gridListControl1.Enabled = false;
this.gridListControl1.Grid.PrepareViewStyleInfo += new GridPrepareViewStyleInfoEventHandler(Grid_PrepareViewStyleInfo);
private void Grid_PrepareViewStyleInfo(object sender, GridPrepareViewStyleInfoEventArgs e)
{
if(!this.ListBox1.Enabled)
{
e.Style.TextColor = SystemColors.GrayText;
}
}