次のサンプルコードは、アクティブシートタブの背景色を赤に設定します。
fpSpread1.Sheets.Count = 3;
FarPoint.Win.Spread.SheetTab st;
st = fpSpread1.TabStrip.ActiveSheetTab;
st.BackColor = Color.Red;
fpSpread1.Sheets.Count = 3
Dim st As FarPoint.Win.Spread.SheetTab
st = fpSpread1.TabStrip.ActiveSheetTab
st.BackColor = Color.Red