Index: sources/gui/qml/components/BaseChart.qml
===================================================================
diff -u -rd5aa2daeb2dfb38d93d128a85618b86855e07239 -r09ec5af58d98d8cd337359482e81045052a5c264
--- sources/gui/qml/components/BaseChart.qml	(.../BaseChart.qml)	(revision d5aa2daeb2dfb38d93d128a85618b86855e07239)
+++ sources/gui/qml/components/BaseChart.qml	(.../BaseChart.qml)	(revision 09ec5af58d98d8cd337359482e81045052a5c264)
@@ -15,6 +15,7 @@
 
 import QtQuick 2.15
 import QtCharts 2.15
+import QtQuick.Shapes 1.15 // Import the Shapes module
 
 import "qrc:/globals"
 
@@ -36,7 +37,7 @@
     readonly property int   minY            : -700
     readonly property int   maxY            : 600
 
-    readonly property int   plotFrequency   : 1000  * 60 // plot every 1 min
+    readonly property int   plotFrequency   : 1000 * 60 // plot every 1 min
 
      // plot current reading at current time
     function plotGraph() {
@@ -146,5 +147,139 @@
             useOpenGL   : true
             width       : 3
         }
+
+        // --- The Vertical Line ---
+        Shape { id: _verticalLine
+            width   : 1
+            height  : _chartView.plotArea.height
+            y       : _chartView.plotArea.y
+            visible : false // Hidden until touched
+
+            ShapePath {
+                strokeColor : "#CA8D36"
+                strokeWidth : 1
+                strokeStyle : ShapePath.DashLine
+                dashPattern : [2, 4]
+                capStyle    : ShapePath.RoundCap
+
+                startX: 1; startY: 0
+                PathLine { x: 1; y: _verticalLine.height }
+            }
+        }
+
+        Row { id: _row
+            anchors.top: parent.top
+            anchors.topMargin: 5
+            anchors.horizontalCenter: parent.horizontalCenter
+            spacing: Variables.defaultMargin
+
+            Text { id: _timeText
+                color: Colors.offWhite
+                font.pixelSize: 22
+                font.weight: Font.Medium
+            }
+
+            Text { id: _line1Text
+                color: _root.lineSeries1Color
+                font.pixelSize: 22
+                font.weight: Font.Medium
+            }
+
+            Text { id: _line2Text
+                color: _root.lineSeries2Color
+                font.pixelSize: 22
+                font.weight: Font.Medium
+            }
+
+            Text { id: _line3Text
+                color: _root.lineSeries3Color
+                font.pixelSize: 22
+                font.weight: Font.Medium
+            }
+        }
+
+        // --- Touch/Mouse Handling Area ---
+        MouseArea {
+            anchors.fill: parent
+            hoverEnabled: true
+
+            onPressed: {
+                _verticalLine.visible = true
+                updateLinePosition(mouse.x, mouse.y)
+            }
+            onPositionChanged: {
+                if (pressed) { updateLinePosition(mouse.x, mouse.y) }
+            }
+
+            function updateLinePosition(mx, my) {
+                if (mx < _chartView.plotArea.x || mx > _chartView.plotArea.x + _chartView.plotArea.width)
+                    return
+
+                _verticalLine.x = mx
+
+                // Convert to data coordinates
+                let line1Value = _chartView.mapToValue(Qt.point(mx, my), _line1)
+                let line2Value = _chartView.mapToValue(Qt.point(mx, my), _line2)
+                let line3Value = _chartView.mapToValue(Qt.point(mx, my), _line3)
+
+                let newDate = new Date( line1Value.x )
+                _timeText.text = qsTr("Time: %1").arg(Qt.formatTime(newDate, "H:mm"))
+
+                let y1 = getYatX( _line1, line1Value.x )
+                let y2 = getYatX( _line2, line2Value.x )
+                let y3 = getYatX( _line3, line3Value.x )
+
+                _line1Text.text = y1 ? y1.toFixed(0) : Variables.emptyEntry
+                _line2Text.text = y2 ? y2.toFixed(0) : Variables.emptyEntry
+                _line3Text.text = y3 ? y3.toFixed(0) : Variables.emptyEntry
+            }
+
+            function getYatX(series, x) {
+                let count = series.count
+
+                // need at least 2 points to interpolate between them
+                if (count < 2)
+                    return null
+
+                // Clamp outside range
+                let first = series.at(0)
+                let last = series.at(count - 1)
+
+                // if x is given before thie first point then return first y
+                if (x <= first.x)
+                    return first.y
+
+                // if x is given after the last point then return last y
+                if (x >= last.x)
+                    return last.y
+
+                // Binary Search for a fast look ip
+                let left = 0
+                let right = count - 1
+
+                while (left <= right) {
+                    let mid = Math.floor((left + right) / 2)
+                    let midPoint = series.at(mid)
+
+                    // found y
+                    if (midPoint.x === x)
+                        return midPoint.y
+
+                    if (midPoint.x < x)
+                        left = mid + 1      // x is larger so discard left half
+                    else
+                        right = mid - 1     // x is smaller so discard right half
+                }
+
+                // if not found then interpolate betweeen them
+                // series.at(right) and series.at(left)
+                let p1 = series.at(right)
+                let p2 = series.at(left)
+
+                // Compute how far between them X is
+                let ratio = (x - p1.x) / (p2.x - p1.x)
+                return p1.y + ratio * (p2.y - p1.y) //compute y
+            }
+        }
     }
 }