Multiwindow manual testing - "Closes windows" close window in order of creation

Description:

The "close windows" button close windows in order of their creation, no matter if the window that should be closed, already was closed manually. 

Steps to reproduce:

1. Run the multiwindow manual test
2. Click on "new window" three times as to create windows ( #0, #1, #2)
3. Click on the "x" in the right corner of window #2
4. Now click on "close window" (nothing should happen, as #2 has already been closed)
5. Click again on "close window" (it should close #1)

Expected behavior:

Clicking on "close window" should only be closing windows that are still open.
Observed behavior:

"Close window" does not take into account the windows that already have been closed.
Special notes:

The test provides some feedback about what is going on in the terminal, but should it still behaves that way? **