Accessing a form's control from a separate thread

Question

I\'m practising on threading and came across this problem. The situation is like this:

1. I have 4 progress bars on a single form, one for downloading a file,

Answer 1

A Control can only be accessed within the thread that created it - the UI thread.

You would have to do something like:

Invoke(new Action(() =>
{
    progressBar1.Value = newValue;
}));

The invoke method then executes the given delegate, on the UI thread.