private void button4_Click(object sender, EventArgs e)
        {
            groupBox3.Visible = true;
            List <COMCategory> cats = new List <COMCategory>();

            if (BLLcategory.GetCategories() != null)
            {
                cats = BLLcategory.GetCategories();
                comboBox1.DataSource    = cats;
                comboBox1.DisplayMember = "CategoryName";
                comboBox1.ValueMember   = "CategoryId";
            }
            List <COMuser> users = new List <COMuser>();

            if (BLLuser.GetUsers() != null)
            {
                users = BLLuser.GetUsers();
                comboBox3.DataSource    = users;
                comboBox3.DisplayMember = "Email";
                comboBox3.ValueMember   = "UserId";
            }
        }
 public List <COMuser> GetUsers()
 {
     return(BLLuser.GetUsers());
 }