C#

delegate void ListItemChangedHandler(string newItemText); // Delegate declaration
class Form2 : Form
{
    public ListItemChangedHandler ListItemChanged = null;

    void onListItemChange(object sender,...)
    {
       if(ListItemChanged != null)
          ListItemChanged(listbox1.Text);  // Calling delegate
    }
    
    // other code
}

class Form1 : Form
{
     void ShowForm2()
     {
        Form2 frm2 = new Form2();
        frm2.ListItemChanged += ListBoxValueChanged; // Subscribing on the delegate instance
     }

     void ListBoxValueChanged(string text)  // This function will be called when value changes in Form2
     {
        yourTextBox.Text = text;
     }

     // other code
}

public delegate string stringGetter(Control c);

public string GetText(Control c) {
    if (c.InvokeRequired) {
        return (string)c.Invoke(new stringGetter(GetText), new object[] { c });
    } else {
        return c.Text;
    }
}

Thread worker = new Thread((ThreadStart)delegate
{
    string str = button1.Text; // Works well as Button.Text property is not using the button's handle
    string str1 = comboBox1.Text; // Error! Because it uses the handle.
});
worker.Start();

N a v a n e e t h wrote:

only required when the call accesses control's handle

Luc Pattyn wrote:

[ADDED]A little experiment confirms a thread can get a button's text without a cross-thread exception being thrown, but not a combobox text. [/ADDED]

Abdaqader wrote:

and I must make Project and I do'nt have any new idea for making the project