[orca-list] When checking "only speak displayed text" Orca doesn't announce the new window with alt + tab

[Alex ARNAUD <aarnaud hypra fr>]

    Hello,
    
    Environment:
    - Orca 3.32, 3.34 and master
    - Debian 9, 10 and testing
    - Marco and Compiz windows managers
    
    Steps to reproduce:
    1) Check "only speak displayed text" in Orca preferences
    2) Open two windows
    3) Hold alt and press tab multiple time
    
    Result:
    Orca stays silent.
    
    Expected result:
    Orca should announce the new window when pressing tab to let the
    user choose on what window he wants to focus.
    
    Best regards.