Question

I am writing an application using C# and WPF. Is there some way that my app can be notified whenever GetActiveWindow changes, or am I stuck with making a thread and monitoring the changes myself?

Answer 1

use Activated event like:

//at window load or at the constructor
this.Activated += OnWindowActivated;

private void OnWindowActivated(object sender, EventArgs e)
{
     //your code here
}

Edit: As you want it to be for any window in the OS. check this similar question.