private void buttonUpdate_Click(object sender, EventArgs e)
        {
            List <User> commiteeMembers = new List <User>();

            for (int i = 0; i < comboBoxCheckedListUpdate.Items.Count; i++)
            {
                if (comboBoxCheckedListUpdate.GetItemChecked(i))
                {
                    commiteeMembers.Add((User)comboBoxCheckedListUpdate.Items[i]);
                }
            }

            List <Topic> selectedTopics = new List <Topic>();

            foreach (int i in listBoxTopics.SelectedIndices)
            {
                string topicName = listBoxTopics.Items[i].ToString();
                selectedTopics.Add(preliminaryController.FindTopicByName(topicName));
            }

            try
            {
                activeConference.Name          = textBoxName.Text;
                activeConference.EndDate       = dateTimePicker.Value;
                activeConference.Topics        = selectedTopics;
                activeConference.ConferenceFee = float.Parse(textBoxFee.Text);
                validator.validate(activeConference);

                preliminaryController.UpdateConference(activeConference);
                MessageBox.Show("Conference has been successfully updated!", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            catch (System.Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
        private void buttonStartConference_Click(object sender, EventArgs e)
        {
            DialogResult dialogResult = MessageBox.Show("Are you sure you want to start the conference?", "Start Conference", MessageBoxButtons.YesNo);

            if (dialogResult == DialogResult.Yes)
            {
                Conference activeConference = preliminaryController.ActiveConference();

                Phase nextPhase = new Phase();
                nextPhase.Deadline = activeConference.EndDate;
                nextPhase.Name     = "PHASEONE";

                activeConference.ActivePhase = nextPhase;

                preliminaryController.UpdateConference(activeConference);

                MessageBox.Show("Conference has successfully started!", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
                Close();
            }
            else if (dialogResult == DialogResult.No)
            {
                //do nothing
            }
        }