@M4RZB4Ni
Hi its all in here
http://doc.qt.io/qt-5/qscrollbar.html#details
But connecting to a random widget will do nothing.

IF u have this case,
user click on Tab
In tab there are many widget so he need to scroll to see last of them, then u just use
a scroll area and put all stuff inside. then it will just work. ScrollArea have scrollbars.
U can control if both horz and vert or just horz.