C# – .Net winform property says Visible but I can’t see it

As per Prerak K's update comment (since deleted):

I guess I have not presented the question properly.

Situation is this: I want to load data into a global variable based on the value of a control. I don't want to change the value of a control from the child thread. I'm not going to do it ever from a child thread.

So only accessing the value so that corresponding data can be fetched from the database.

The solution you want then should look like:

UserContrl1_LOadDataMethod()
{
    string name = "";
    if(textbox1.InvokeRequired)
    {
        textbox1.Invoke(new MethodInvoker(delegate { name = textbox1.text; }));
    }
    if(name == "MyName")
    {
        // do whatever
    }
}

Do your serious processing in the separate thread before you attempt to switch back to the control's thread. For example:

UserContrl1_LOadDataMethod()
{
    if(textbox1.text=="MyName") //<<======Now it wont give exception**
    {
        //Load data correspondin to "MyName"
        //Populate a globale variable List<string> which will be
        //bound to grid at some later stage
        if(InvokeRequired)
        {
            // after we've done all the processing, 
            this.Invoke(new MethodInvoker(delegate {
                // load the control with the appropriate data
            }));
            return;
        }
    }
}

There are several problems here. First of all, when ShowInTaskbar property is set to false, an invisible window gets created and assigned as a parent of current window. This invisible window's icon is displayed when switching between windows.

You can catch that window with Interop and set it's icon like this:

private void Window_Loaded(object sender, RoutedEventArgs e) {
    SetParentIcon();
}

private void SetParentIcon() {
    WindowInteropHelper ih = new WindowInteropHelper(this);
    if(this.Owner == null && ih.Owner != IntPtr.Zero) { //We've found the invisible window
        System.Drawing.Icon icon = new System.Drawing.Icon("ApplicationIcon.ico");
        SendMessage(ih.Owner, 0x80 /*WM_SETICON*/, (IntPtr)1 /*ICON_LARGE*/, icon.Handle); //Change invisible window's icon
    }
}

[DllImport("user32.dll")]
private static extern int SendMessage(IntPtr hWnd, int wMsg, IntPtr wParam, IntPtr lParam);

The other problems for you to think about would be:

1. Find out what happens when ShowInTaskbar property changes at runtime;
2. Extract an icon from your window rather than from file;