Index: sources/gui/qml/compounds/ValueAdjuster.qml
===================================================================
diff -u -rb16fd955f65d83321decdc54bd3d5695fc81c32c -rc43d24c50f4344348d36d8ae9273797f4557356a
--- sources/gui/qml/compounds/ValueAdjuster.qml	(.../ValueAdjuster.qml)	(revision b16fd955f65d83321decdc54bd3d5695fc81c32c)
+++ sources/gui/qml/compounds/ValueAdjuster.qml	(.../ValueAdjuster.qml)	(revision c43d24c50f4344348d36d8ae9273797f4557356a)
@@ -31,6 +31,7 @@
     property bool   canOff      : false
     property bool   canRefresh  : false
     property alias  textColor   : _text.color
+    property bool   grabbed     : false
 
     QtObject { id: _private
         // fix floating-point precision issue
@@ -169,10 +170,10 @@
         }
 
         MouseArea { id: _sliderMouseArea
-            property bool grabbed: false
 
             anchors.fill        : parent
             pressAndHoldInterval: 0
+            drag.axis           : Drag.XAxis      // only horizontal
 
             onClicked: {
                 if ( _root.editable ) { didActiveChange(true); focus = true }
@@ -181,18 +182,18 @@
             }
 
             onReleased: {
-                _sliderMouseArea.grabbed = false
+                _root.grabbed = false
                 _slider.opacity = 0
             }
 
             onPressAndHold: {
                 if ( _root.editable ) { didActiveChange(true); focus = true }
 
-                _sliderMouseArea.grabbed = true
+                _root.grabbed = true
             }
 
             onPositionChanged: {
-                if (grabbed) {
+                if (_root.grabbed) {
                     if ( _slider.opacity === 0 ) { _animator.start() }
 
                     _slider.pos = Math.max(0, Math.min(1, mouse.x / parent.width))
@@ -203,7 +204,7 @@
             }
 
             onExited: {
-                if ( ! _sliderMouseArea.grabbed ) {
+                if ( ! _root.grabbed ) {
                     _animator.stop()
                     _slider.opacity = 0
                 }
@@ -215,7 +216,7 @@
             from    : 0
             to      : 1
             duration: 350
-            running : _sliderMouseArea.grabbed
+            running : _root.grabbed
         }
 
         Behavior on opacity { NumberAnimation { duration: 200 } }