Bug#665004: xserver-xorg-input-synaptics: scrolling stopped working after upgrade 1.5.0 --> 1.5.99

[Dario Alessio Menin <darioalessio.menin@gmail.com>]

I've found a partial workaround (the old version still behaves better), I don't know if it could be useful to find the problem: In KDE System Settings -> Input Devices -> Touchpad -> scrolling -> Move distance to scroll a single line -> set to 25-30. On my machine the touchpad returned partially functional, scrolling at a slow speed remains very difficult.

full configuration:

$ synclient -l
Parameter settings:
    LeftEdge                = 1752
    RightEdge               = 5192
    TopEdge                 = 1620
    BottomEdge              = 4236
    FingerLow               = 25
    FingerHigh              = 30
    FingerPress             = 256
    MaxTapTime              = 180
    MaxTapMove              = 221
    MaxDoubleTapTime        = 180
    SingleTapTimeout        = 180
    ClickTime               = 100
    FastTaps                = 0
    EmulateMidButtonTime    = 75
    EmulateTwoFingerMinZ    = 282
    EmulateTwoFingerMinW    = 7
    VertScrollDelta         = 30
    HorizScrollDelta        = 100
    VertEdgeScroll          = 0
    HorizEdgeScroll         = 0
    CornerCoasting          = 0
    VertTwoFingerScroll     = 1
    HorizTwoFingerScroll    = 0
    MinSpeed                = 1
    MaxSpeed                = 1.75
    AccelFactor             = 0.1398
    TrackstickSpeed         = 40
    EdgeMotionMinZ          = 30
    EdgeMotionMaxZ          = 160
    EdgeMotionMinSpeed      = 1
    EdgeMotionMaxSpeed      = 401
    EdgeMotionUseAlways     = 0
    TouchpadOff             = 0
    LockedDrags             = 0
    LockedDragTimeout       = 5000
    RTCornerButton          = 0
    RBCornerButton          = 0
    LTCornerButton          = 0
    LBCornerButton          = 0
    TapButton1              = 1
    TapButton2              = 3
    TapButton3              = 2
    ClickFinger1            = 1
    ClickFinger2            = 1
    ClickFinger3            = 1
    CircularScrolling       = 0
    CircScrollDelta         = 0.100007
    CircScrollTrigger       = 0
    CircularPad             = 0
    PalmDetect              = 0
    PalmMinWidth            = 10
    PalmMinZ                = 200
    CoastingSpeed           = 0
    CoastingFriction        = 50
    PressureMotionMinZ      = 30
    PressureMotionMaxZ      = 160
    PressureMotionMinFactor = 1
    PressureMotionMaxFactor = 1
    GrabEventDevice         = 1
    TapAndDragGesture       = 1
    AreaLeftEdge            = 0
    AreaRightEdge           = 0
    AreaTopEdge             = 0
    AreaBottomEdge          = 0
    HorizHysteresis         = 25
    VertHysteresis          = 25
    ClickPad                = 0