Hi Shalini,
Thanks for considering Aspose.
1). Well you don't need any method. If the list box has more items than its height, scrollbars automaticlally attached to it.
2). You may use ListBox.IsSelected(itemindex) method to check if an item is selected or not. Kindly check the following sample example for your reference. I used a template file attached:
//We have a list box which has three items selected i.e., first, third and fifth.
Workbook workbook = new Workbook();
workbook.Open("d:\\test\\tstlistbox1.xls");
Worksheet sheet = workbook.Worksheets[0];
Aspose.Cells.ListBox lst = (Aspose.Cells.ListBox)sheet.Shapes[0];
MessageBox.Show(lst.LinkedCell);
MessageBox.Show(lst.InputRange);
MessageBox.Show(lst.SelectedIndex.ToString());
MessageBox.Show(lst.ItemCount.ToString());
bool check0 = lst.IsSelected(0);
bool check1 = lst.IsSelected(1);
//true
MessageBox.Show(check0.ToString());
//false
MessageBox.Show(check1.ToString());
lst.SelectionType = SelectionType.Multi;
//Select the second item.
lst.SelectedItem(1, true);
//Select the 6th item (last item)
lst.SelectedItem(5,true);
check1 = lst.IsSelected(1);
bool check5 = lst.IsSelected(5);
MessageBox.Show(check1.ToString());//now it should be true.
MessageBox.Show(check5.ToString());//should be true now.
Thank you.