private void buttonMaintainCategory_Click(object sender, EventArgs e)
        {
            formCategory formCategory = new formCategory();

            formCategory.Show();
            this.Hide();
        }
 private void catagoryToolStripMenuItem_Click(object sender, EventArgs e)
 {
     if (_formCategory.IsDisposed)
     {
         _formCategory = new formCategory();
     }
     //_formCategory.MdiParent = this;
     _formCategory.ShowDialog();
     _formCategory.BringToFront();
 }