Bug made MDI not usable

I noticed many bugs around MDI

First around tabs that are confirmed this same like Pyside2 here

1. https://bugreports.qt.io/browse/QTBUG-44630
2. https://bugreports.qt.io/browse/QTBUG-13257

 
I using this code to create tabs
  
    def createMditab(self):
        labels = []

        tab = ['test 1','test 2','test 3','test 4','test 5','test 6','test 7','test 8','test 9']
        len_ = len(tab)

        for i in range(len_):

            labels.append(QtWidgets.QLabel())
            labels[i].setText(tab[i] )
            base = Chart(labels[i])
            Chart(labels[i]).SetChartName(tab[i] )

            self.ui.mdiArea.addSubWindow(base).setWindowTitle(tab[i])
 
 
The focus on tabs is missunderstanded here (last active other not clicable, not scrollable, and first other focus).
mdi_test_1 - bug.png
 
When closing (right mouse context click) test tab 9 then activated tab 8 but other have closed focus.
mdi_test_1 scrol 9 to 6 - bug.png
mdi_test_1 closed 9 - bug.png
 
When tested this in previous Pyside2 no problem, but meet other: sroling fast tabs made tabs names "cloned" level uper (looks like tetris effect in high frequency) - when on tab exist widget with graphic or opengl then repeating with this like bacground where betwen changes is white coulour blinking (I remeber reported this tybe effect/bug in other issues as negative effect for GUI/UX as very not user friendly mad him angry).
Activation for tabs backing on QT app when on Windows change focus to other app or dir in down belt (click) and focusing agai QT app (clikc)
 
Next. When betwen MDIwidgets on left and right exist docks, then strange effect on graphic/opengl when scalig docks size - the tabs blinking quickly and disaperaing.
 
If exist many tabs the arrows < > to naviagte with tabs made that these tabs ar under arrwos not text to arrows btns. Sometimes are next to, some times in half of btns - when scaling docks both side or whole app window then backing to normal position (next to tabs).
mdi_arrows - bug. When arrows moved tabs list to max left possition then left btn is ugly like disapread background of btn or with alpha 100%
 

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1. eample_1.zip