private void Btncleartextnhanvien_Click(object sender, EventArgs e)
 {
     OptimizedPerformance.ClearAllText(tabControl1);
 }
 private void Btncleartextthucuong_Click(object sender, EventArgs e)
 {
     lblpaththucuong.Text = "";
     OptimizedPerformance.ClearAllText(tabControl1);
 }
 private void IconButton3_Click(object sender, EventArgs e)
 {
     OptimizedPerformance.ClearAllText(this);
 }