E.g. Open PlayOnMac, click on Setup icon at toolbar, minimizes the PlayOnMac and restore it again. The main window of PlayOnMac is shown but the Setup window will be behind it. An advanced user just drag the window of PlayOnMac to see Setup screen, but an average user will not know why he/she is clicking on "Setup" button and it's not "working". PlayOnMac should check if a child window is opened and restore it right after the user click after restoring PlayOnMac window.
It also happens that when clicking on Setup icon, it opens behind the PlayOnMac instead of being opened right in front of it. The PlayOnMac should check if a child window is in front of PlayOnMac after loading the child window.