Core: Set the SH_Slider_AbsoluteSetButtons style for QSlider

This way when the user clicks on the slider with the mouse the slider
jumps under the mouse and not left and right according to the slider
page.

Change-Id: If36f9d8ea82f5b200e2322758f4fc25aef5e1a04
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/coreplugin/manhattanstyle.cpp

@@ -442,6 +442,10 @@ int ManhattanStyle::styleHint(StyleHint hint, const QStyleOption *option, const
         ret = QGuiApplication::keyboardModifiers()
               == (HostOsInfo::isMacHost() ? Qt::MetaModifier : Qt::ControlModifier);
         break;
+    case QStyle::SH_Slider_AbsoluteSetButtons:
+        // Make QSlider jump on left mouse click
+        ret = Qt::LeftButton | Qt::MiddleButton | Qt::RightButton;
+        break;
     default:
         break;
     }