title: Don't accept any operation in Main, unless other form closses
body: <p>My question is that as in IDM and Winrar, when we click on any option like on "Add" in winrar and in IDM on "Add URL". The main window stays in the background but cannot accept user click and we have to close the operation in front first in order to make interaction again with main form.</p>
  
  <p>I want the same with my windows forms and I am not using parent child relation.</p>