qt - Style QComboBox's sub-control down-arrow when mouse is hovering over the QComboBox via QSS -

i know how style qcombobox when mouse hovering doing:

pcombobox->setstylesheet(pcombobox->stylesheet()+qstring("  qcombobox:hover{css style here}")) 

and know style qcombobox's sub-control down-arrow's style via:

pcombobox->setstylesheet(pcombobox->stylesheet()+qstring("  qcombobox::down-arrow{css style here}")) 

but don't know how style qcombobox's sub-control down-arrow when mouse hovering on qcombobox via qss. have idea?

i don't know qss powerful enough this(i think no), eventfilter can easy:

bool mainwindow::eventfilter(qobject *obj, qevent *event) {      if (obj == ui->combobox && event->type() == qevent::enter)     {         //user enters combobox, apply stylesheet         ui->combobox->setstylesheet("qcombobox::down-arrow{background-color: red}");     }     else         if(event->type() == qevent::leave)//user leaves combobox, set default settings             ui->combobox->setstylesheet("");      return qobject::eventfilter(obj, event); } 

to use eventfilter should also:

protected:     bool eventfilter(qobject *obj, qevent *event);//in header 

and

qapp->installeventfilter(this);//in constructor