MdiSubWindows

[DmitryNik]

Sorry, guys about that, my mistake. OK, here is the code:

foreach(QMdiSubWindow *sub, this->mdiWin->subWindowList())
    {
        if(sub->isActiveWindow())
        {
            sub->close();
            break;
        }
    }

foreach(QMdiSubWindow *sub, this->mdiWin->subWindowList())
    {
        if(sub->isActiveWindow())
        {
            sub->close();
            break;
        }
    }

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So in this case the window, which was opened first, will be closed, even it's not an active window. In this code "this" - is window, which central widget is MdiArea's object (mdiWin). In each sub-window we have a simple widget, let's say, PushButton.