private void ToolStripMenuItemQuanLyNangLuong_Click(object sender, EventArgs e)
 {
     if (ttLuong == null || ttLuong.IsDisposed)
     {
         ttLuong = new FrmDanhSachNangLuong();
     }
     ttLuong.MdiParent = this;
     ttLuong.Show(dockPanelMain);
 }
 private void btnNangLuong_Click(object sender, EventArgs e)
 {
     if (ttLuong == null || ttLuong.IsDisposed)
     {
         ttLuong = new FrmDanhSachNangLuong();
     }
     ttLuong.MdiParent = this;
     ttLuong.Show(dockPanelMain);
     this.Activate();
 }