Index: sources/gui/qml/components/RangeSlider.qml
===================================================================
diff -u -r642f08650a7a88ad6a2305fdea6bd18365aab5c7 -r5d7dd96636bc7a647c61a43bb04ed25f5c2f6e7e
--- sources/gui/qml/components/RangeSlider.qml	(.../RangeSlider.qml)	(revision 642f08650a7a88ad6a2305fdea6bd18365aab5c7)
+++ sources/gui/qml/components/RangeSlider.qml	(.../RangeSlider.qml)	(revision 5d7dd96636bc7a647c61a43bb04ed25f5c2f6e7e)
@@ -51,6 +51,8 @@
     property real   maxValueLowerBound    : 0
     property real   maxValueUpperBound    : 0
 
+    property bool   lowerBoundValid : true
+    property bool   upperBoundValid : true
 
     property int    curHandler  : RangeSlider.HandlerOption.None    ///< current active slider handler
     property int    diameter    : Variables.progressbarHandler      ///< handlers diameter
@@ -103,15 +105,15 @@
     minimum         : 0
     maximum         : 0
 
-    /// Lable of the minimum of range
+    /// The label under the rangeSlider for minimum value
     minText {
         visible          : true
         anchors.topMargin: Variables.sliderTextMargin
         font.pixelSize   : Fonts.fontPixelSliderMarker
         font.bold        : false
     }
 
-    ///< Lable of the maximum of range
+    /// The label under the rangeSlider for maximum value
     maxText {
         visible          : true
         anchors.topMargin: Variables.sliderTextMargin
@@ -315,6 +317,20 @@
         setBound(newX)
     }
 
+    function getColor(vIsActive, vIsValid) {
+        let color = Colors.textDisableButton
+        if ( vIsActive ) {
+            if ( vIsValid ) {
+                color = Colors.textMain
+            }
+            else {
+                color = Colors.createTreatmentInvalidParam
+            }
+        }
+        return color
+    }
+
+
     /// The main range rectangle bar - This is the "highlighted" area of the slider
     RangeRect { id: _rangeRect
         property alias  lowerBound  : _rangeRect.minimum
@@ -332,13 +348,15 @@
 
         decimal : _root.decimal
 
-        minText {
-            visible: false
+        minText { // The minimum value label above the handle
+            visible          : false
             anchors.topMargin: -60
+            color            : _root.getColor((_root.minAdjusted && _root.maxAdjusted), lowerBoundValid)
         }
-        maxText {
-            visible: false
+        maxText { // the maximum value label above the handle
+            visible          : false
             anchors.topMargin: -60
+            color            : _root.getColor((_root.minAdjusted && _root.maxAdjusted), upperBoundValid)
         }
 
         // propagation is not working on drag !