Scrollbar thumb shows as hovered after mouse is released outside the thumb

New hover area check (part of the linked MR)

For vertical scrollbar:
hovered == (x is inside the TROUGH) && (y is inside the THUMB)

For horizontal scrollbar:
hovered == (x is inside the THUMB) && (y is inside the TROUGH)

This means we're also providing an error margin along the "scrolling" axis (x for vert scrollbar, y for horiz scrollbar), where it's enough for the mouse to be inside the trough instead of inside the thumb.

This makes it easier to hover and drag both using mouse and touch, as it currently provides an additional 3dp of interactive area on each side of the thumb (thumb's width is 8dp, trough's width is 14dp at the moment)

This bug was fixed in the package ubuntu-ui-toolkit 1.3.2104+15.04.20160919.3 in https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/stable-phone-overlay

---------------

ubuntu-ui-toolkit (1.3.2104+15.04.20160919.3) vivid; urgency=medium

  [ Andrea Bernabei ]
  * Scrollbar: more hover related bugfixes and unit tests.
    Fixes: LP: #1616868, LP: #1616926

  [ Christian Dywan ]
  * QuickUtils.rootObject() needs to handle QQuickWindow. Fixes: LP: #1617745
  * Correctly test and fix trigger override of ComboButton. Fixes: LP: #1614045

  [ Zoltan Balogh ]
  Increase the top marging when scrolling upwards. Fixes LP: 1618581

  [ Timo Jyrinki ]
  * Temporarily skip unit tests on xenial while not all MPs to fix Qt 5.6 issues
    have landed yet.

  [ Michael Terry ]
  * Make ActivityIndicator spinner blue instead of orange. Fixes: LP: #1577828.

  [ Loïc Molinari ]
  * Changed src/ directory layout. Made the source directory layout consistent
    with Qt libs. The C++ libraries have been moved to src/ and the QML modules
    to src/imports/. That also makes it easier to differentiate between modules
    and libraries since we have a bunch of them now.
  * Moved internal tools meant to generate code for the toolkit lib from the QML
    module directory to the lib directory where it makes more sense.
  * Fixed the build as a Qt submodule.
  * Fixed, cleaned up and standardised header inclusions. Apart from the clean
    up and the readability improvements, this fixes a bunch of broken private
    header inclusions (#include "foo_p.h" in private headers instead of
    "private/foo_p.h" or better ), now all the private headers of the UITK can
    be included by the users withour compilation issues. It also removes a bunch
    of direct includes from sources and a few INCLUDEPATHs hacks.See the CODING
    file for more details.
  * Cleaned up ubuntu_qt_module.prf and the libs using it.
    1/ Moved the common config options from the pro files to the prf file to
       avoid duplications and simplify the files.
    2/ Removed the useless "TEMPLATE=lib" and "load(qt_build_config)" lines from
       the pro files since it's done for us by qt_module.prf.
    3/ Use QT= instead of QT*= since it's well defined that by default its
       content is "core gui".
    4/ Prefixed headers and sources by $$PWD/ and sorted the lines
       alphabetically.
    5/ Merged the SOURCES declarations in UbuntuToolkit.pro.
    6/ Removed the useless "DEFINES += QT_USE_QSTRINGBUILDER" line from
       UbuntuToolkit.pro since it's done for us by qt_module.prf.
    7/ Removed the useless "QMAKE_CXXFLAGS -= -Werror=deprecated-declarations"
       and "DEFINES -= QT_DEPRECATED_WARNINGS" lines from UbuntuToolkit.pro
       since it's already done in ubuntu_qt_module.prf.
    8/ Added a few comments.
  * Made use of Qt builtin to check GCC version.

  [ Tim Peeters ]
  * Improve the initialization of Action when it gets both iconName and
    iconSource from an external component when iconSource is undefined. This
    fixes the some times missing overflow button in the ActionBar with Qt 5.6.
    I also removed action: modelData from the OverflowPanel because this is
    a...

This bug was fixed in the package ubuntu-ui-toolkit - 1.3.2104+16.10.20160919.3

---------------
ubuntu-ui-toolkit (1.3.2104+16.10.20160919.3) yakkety; urgency=medium

  [ Andrea Bernabei ]
  * Scrollbar: more hover related bugfixes and unit tests.
    Fixes: LP: #1616868, LP: #1616926

  [ Christian Dywan ]
  * QuickUtils.rootObject() needs to handle QQuickWindow. Fixes: LP: #1617745
  * Correctly test and fix trigger override of ComboButton. Fixes: LP: #1614045

  [ Zoltan Balogh ]
  Increase the top marging when scrolling upwards. Fixes LP: 1618581

  [ Timo Jyrinki ]
  * Temporarily skip unit tests on xenial while not all MPs to fix Qt 5.6 issues
    have landed yet.

  [ Michael Terry ]
  * Make ActivityIndicator spinner blue instead of orange. Fixes: LP: #1577828.

  [ Loïc Molinari ]
  * Changed src/ directory layout. Made the source directory layout consistent
    with Qt libs. The C++ libraries have been moved to src/ and the QML modules
    to src/imports/. That also makes it easier to differentiate between modules
    and libraries since we have a bunch of them now.
  * Moved internal tools meant to generate code for the toolkit lib from the QML
    module directory to the lib directory where it makes more sense.
  * Fixed the build as a Qt submodule.
  * Fixed, cleaned up and standardised header inclusions. Apart from the clean
    up and the readability improvements, this fixes a bunch of broken private
    header inclusions (#include "foo_p.h" in private headers instead of
    "private/foo_p.h" or better ), now all the private headers of the UITK can
    be included by the users withour compilation issues. It also removes a bunch
    of direct includes from sources and a few INCLUDEPATHs hacks.See the CODING
    file for more details.
  * Cleaned up ubuntu_qt_module.prf and the libs using it.
    1/ Moved the common config options from the pro files to the prf file to
       avoid duplications and simplify the files.
    2/ Removed the useless "TEMPLATE=lib" and "load(qt_build_config)" lines from
       the pro files since it's done for us by qt_module.prf.
    3/ Use QT= instead of QT*= since it's well defined that by default its
       content is "core gui".
    4/ Prefixed headers and sources by $$PWD/ and sorted the lines
       alphabetically.
    5/ Merged the SOURCES declarations in UbuntuToolkit.pro.
    6/ Removed the useless "DEFINES += QT_USE_QSTRINGBUILDER" line from
       UbuntuToolkit.pro since it's done for us by qt_module.prf.
    7/ Removed the useless "QMAKE_CXXFLAGS -= -Werror=deprecated-declarations"
       and "DEFINES -= QT_DEPRECATED_WARNINGS" lines from UbuntuToolkit.pro
       since it's already done in ubuntu_qt_module.prf.
    8/ Added a few comments.
  * Made use of Qt builtin to check GCC version.

  [ Tim Peeters ]
  * Improve the initialization of Action when it gets both iconName and
    iconSource from an external component when iconSource is undefined. This
    fixes the some times missing overflow button in the ActionBar with Qt 5.6.
    I also removed action: modelData from the OverflowPanel because this is
    already set automatically in ActionSelectionPopover after everything is
    initia...