public PreviewPanel(Timetable timetable)
{
InitializeComponent();
if (!Properties.Settings.Default.ImportUnselectable)
{
labelImportNotice.Visible = true;
}
// build tree
timetable.BuildTreeView(treePreview);
// and scroll back to the top
treePreview.Nodes[0].EnsureVisible();
// clear details box
textBoxTreeDetails.Text = "";
timetableControl.Clear();
}