private void addCategoryItemButton_Click(object sender, EventArgs e)
{
this.Hide();
CategoryForm aCategoryForm = new CategoryForm();
aCategoryForm.Show();
}
private void categoryStockOutButton_Click(object sender, EventArgs e)
{
CategoryForm categoryForm = new CategoryForm();
this.Close();
thread = new Thread(OpenCategoryForm);
thread.SetApartmentState(ApartmentState.STA);
thread.Start();
}