Add showTouchAreas support

src/QmlControls/QGCToolBarButton.qml

@@ -10,6 +10,7 @@
 import QtQuick          2.3
 import QtQuick.Controls 2.4
 
+import QGroundControl               1.0
 import QGroundControl.Controls      1.0
 import QGroundControl.Palette       1.0
 import QGroundControl.ScreenTools   1.0
@@ -31,8 +32,10 @@ Button {
     onCheckedChanged: checkable = false
 
     background: Rectangle {
-        anchors.fill: parent
+        anchors.fill:   parent
-        color:  button.checked ? qgcPal.buttonHighlight : Qt.rgba(0,0,0,0)
+        color:          button.checked ? qgcPal.buttonHighlight : Qt.rgba(0,0,0,0)
+        border.color:   "red"
+        border.width:   QGroundControl.corePlugin.showTouchAreas ? 3 : 0
     }
 
     contentItem: Row {