Fix telemetry bar sizing

src/QmlControls/HorizontalFactValueGrid.qml

@@ -20,10 +20,6 @@ import QGroundControl.Palette       1.0
 import QGroundControl.FlightMap     1.0
 import QGroundControl               1.0
 
-// Note: This control will spit out qWarnings like this: "QGridLayoutEngine::addItem: Cell (0, 1) already taken"
-// This is due to Qt bug https://bugreports.qt.io/browse/QTBUG-65121
-// If this becomes a problem I'll implement our own grid layout control
-
 T.HorizontalFactValueGrid {
     id:                     _root
     Layout.preferredWidth:  topLayout.width
@@ -80,7 +76,7 @@ T.HorizontalFactValueGrid {
                             function recalcWidth() {
                                 var newMaxWidth = 0
                                 for (var i=0; i<valueRepeater.count; i++) {
-                                    newMaxWidth = Math.max(newMaxWidth, valueRepeater.itemAt(0).contentWidth)
+                                    newMaxWidth = Math.max(newMaxWidth, valueRepeater.itemAt(i).contentWidth)
                                 }
                                 maxWidth = Math.min(maxWidth, newMaxWidth)
                             }
@@ -126,6 +122,7 @@ T.HorizontalFactValueGrid {
                     Layout.preferredHeight: ScreenTools.minTouchPixels
                     Layout.preferredWidth:  parent.width
                     text:                   qsTr("+")
+                    enabled:                (_root.width + (2 * (_rowButtonWidth + _margins))) < screen.width
                     onClicked:              appendColumn()
                 }
 
@@ -151,6 +148,7 @@ T.HorizontalFactValueGrid {
                 Layout.fillWidth:       true
                 Layout.preferredHeight: parent.height
                 text:                   qsTr("+")
+                enabled:                (_root.height + (2 * (_rowButtonHeight + _margins))) < (screen.height - ScreenTools.toolbarHeight)
                 onClicked:              appendRow()
             }