C#

public partial class Form1 : Form
        {            
            public Form1()
            {
                InitializeComponent();
            }

            private void button1_Click(object sender, EventArgs e)
            {
                using (Form2 f2 = new Form2())
                {
                    f2.ShowDialog();
                    //f2.Show(); //this doesn't work because ShowDialog is required to stop the process and wait for input, show to show the form and moves on
                    label1.Text = f2.TextValue;
                }
            }
        }
        
        public partial class Form2 : Form
        {
            public string TextValue
            {
                get { return textBox1.Text; }
                set { textBox1.Text = value; }
            }

            public string LabelValue
            {
                get { return label1.Text; }
                set { label1.Text = value; }
            }

            public Form2() 
            { 
                InitializeComponent(); 
            }
        }

Member 10400691 wrote:

It looks like Open XML doesn't support older version than 2007 office.

public DataTable LoadValueConfig(string ControlName, string ParentName, string FormName)
        {
            DataTable _dt = new DataTable();
            _dt.Columns.Add("Name");
            _dt.Columns.Add("Value");
            
            //Move to root node
            _xmlNavi.MoveToRoot();
            //move to windowConfig Node
            _xmlNavi.MoveTo(_xmlNavi.SelectSingleNode("WindowConfig"));
            //if node of form exists move to it
            if (FormName != "") { _xmlNavi.MoveTo(_xmlNavi.SelectSingleNode(FormName)); }
            //if node of parent exists move to it e.g. bsAdminTest
            _xmlNavi.MoveTo(_xmlNavi.SelectSingleNode(ParentName));
            // if control Name exists move to it e.g. switchButton1
            if (_xmlNavi.MoveTo(_xmlNavi.SelectSingleNode(ControlName)))
            {
                _xmlNavi.MoveTo(_xmlNavi.SelectSingleNode(ControlName));
                //Move to first attribute
                _xmlNavi.MoveToFirstAttribute();
                // move through all Attributes and save the values into the DataTable
                do
                {
                    if (_xmlNavi.Value != "")
                    {
                        _dt.Rows.Add(_xmlNavi.Name, _xmlNavi.Value);
                    }
                // while able to move to next Attribute
                } while(_xmlNavi.MoveToNextAttribute());
            }
            
            return _dt;
        }

<WindowConfig>
  <kopiefrmHauptfenster Position="460:21" Size="878:1170" WindowState="Normal">
    <checkBoxItem1 chBoxCheck="True" />
    <bsAdminTest Active="False">
      <switchButton1 switch="False" />
      <richTextBoxEx1 Text="" />
    </bsAdminTest>
    <Project Active="True">
      <navigationPane1 CheckedButton="Projekte" Expanded="True" />
      <expandablePanel1 Expanded="True" />
    </Project>
  </kopiefrmHauptfenster>
</WindowConfig>