iterating through open windows in wpf

i'm developing an application (wpf) that have 3 windows. in the main window user can open other window. when user wants to open window1 i'm create an instance of window1 and showing up that

var win1 = new Window1();
win1.Owner = this;
win1.Show();

now when user wants to close app, i want to iterate through each open window and check if that window isn't busy (or if is busy wait to complete operation) close that window and t开发者_运维知识库hen close application. my question is how to iterating through open windows? maybe using this:

foreach (var window in Application.Current.Windows)
{
    window.
}

but how i can detect window is Window1 or Window2?

You can do

if(window is Window1)
{
   //window is of type 'Window1'!
}

Inside the 'foreach' loop.