Validation support

src/FactSystem/FactControls/FactTextField.qml

 import QtQuick 2.2
 import QtQuick.Controls 1.2
 import QtQuick.Controls.Styles 1.2
+import QtQuick.Dialogs 1.2
+
 
 import QGroundControl.FactSystem 1.0
 import QGroundControl.Palette 1.0
 import QGroundControl.Controls 1.0
 
 QGCTextField {
-    property Fact fact: null
-    text: fact.valueString
+    id: _textField
+
+    property Fact   fact:           null
+    property string _validateString
+
+    text:       fact.valueString
     unitsLabel: fact.units
-    onEditingFinished: fact.value = text
+
+    onEditingFinished: {
+        if (qgcView) {
+            var errorString = fact.validate(text, false /* convertOnly */)
+            if (errorString == "") {
+                fact.value = text
+            } else {
+                _validateString = text
+                qgcView.showDialog(editorDialogComponent, "Invalid Parameter Value", 50, StandardButton.Save)
+            }
+        } else {
+            fact.value = text
+            fact.valueChanged(fact.value)
+        }
+    }
+
+    Component {
+        id: editorDialogComponent
+
+        ParameterEditorDialog {
+            validate:       true
+            validateValue:  _validateString
+            fact:           _textField.fact
+        }
+    }
 }

src/QmlControls/QGCView.qml

@@ -37,7 +37,8 @@ import QGroundControl.FactControls 1.0
 FactPanel {
     id: __rootItem
 
-    property bool completedSignalled: false
+    property var qgcView:               __rootItem  /// Used by Fact controls for validation dialogs
+    property bool completedSignalled:   false
 
     property var viewPanel