Scroll-bar behaviour

[Renaud (Ron) OLGIATI]

Running various programmes under XFCE, I now find myself since a recent upgrade confronted to a variety of different behaviours when clicking in the scrollbar above or below the thumb, in the hope of scrolling one screen up or down.

And I find it completely counter-intuitive that the same action in the same desktop environment gives completely different results depending on which programme it is applied to:

Firefox, Kompozer, Gramps
	Left click: scroll one screen, Right click: nothing

Xfce4-terminal, Transmission, Evince, VLC
	Left click: scroll one screen, Right click: scroll half a line

ClawsMail, Clawsker, PCmanFM, LibreOffice, EasyABC, Bulk rename, Mousepad, Thunar, Xfce-task-manager, Gftp 
	Left click: scroll to cursor, Right click: scroll one screen

Calibre 
	Left click: scroll one screen, Right click: Menu offering various scroll options

So my query: Is there a way to make them all more or less behave the same way, the way it used to work before, and ignoring the right-click, scroll one screen when left-clicking in the scroll-bar ?
 
Cheers,
 
Ron.
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