title: Using NSApplication runModalForWindow multiple times
body: <p>I am wondering whether it is allowed to start multiple modal loops using runModalForWindow(). In my application, I have the following setup: When the user presses button A in the non-modal window A, modal window B will be opened using runModalForWindow(). In modal window B, there is a button B. If the user presses this button B, modal window C will be opened using runModalForWindow(). While modal window C is open, windows A and B shall be blocked from user input and while modal window B is open, window A shall be blocked.</p>
  
  <p>This kind of works with runModalForWindow() but there's a little issue that I've encountered which makes me wonder whether what I'm doing here is allowed. While modal window C is opened, I can actually move modal window B in front of modal window C. B doesn't accept any input but it actually can be moved in front of C. Window A, however, can never be moved in front of B (or C)... it always stays in the background.</p>
  
  <p>Does anybody have an idea why B can be moved in front of C whereas A can never be moved in front of B or C? Is it allowed to use runModalForWindow() several times?</p>