Question

Edited : got it worked.
Generic Collections to be used as a parameter of invoke command

—
Removed the brackets from … SetListDelegate(SetList) in the invoke command of mine

Answer 1

You need to name your method parameter. And you are missing the generic argument.

Something like this will do

public delegate void SetListDelegate<T>(List<T> l );

public void SetList<T> (List<T> l)
{
    if ( lstW.InvokeRequired)
        lstW.Invoke(new SetListDelegate<T>(SetList<T>), l);
    else
        lstW.Items.AddRange(l);
}

Edit:
If this is contained in a class with the generic argument <T> you don’t need it on the delegate or the method.