Cancel polygon edit in appropriate places

src/FlightMap/FlightMap.qml

@@ -221,8 +221,7 @@ Map {
 
             var polygonPath = polygonDrawerPolygon.path
             polygonPath.pop() // get rid of drag coordinate
-            polygonDrawer._clearPolygon()
-            polygonDrawer.drawingPolygon = false
+            _cancelCapturePolygon()
             polygonDrawer._callbackObject.polygonCaptureFinished(polygonPath)
             return true
         }
@@ -292,12 +291,27 @@ Map {
         }
 
         function finishAdjustPolygon() {
+            _cancelAdjustPolygon()
+            polygonDrawer._callbackObject.polygonAdjustFinished()
+        }
+
+        /// Cancels an in progress draw or adjust
+        function cancelPolygonEdit() {
+            _cancelAdjustPolygon()
+            _cancelCapturePolygon()
+        }
+
+        function _cancelAdjustPolygon() {
             polygonDrawer.adjustingPolygon = false
             for (var i=0; i<polygonDrawer._vertexDragList.length; i++) {
                 polygonDrawer._vertexDragList[i].destroy()
             }
             polygonDrawer._vertexDragList = []
-            polygonDrawer._callbackObject.polygonAdjustFinished()
+        }
+
+        function _cancelCapturePolygon() {
+            polygonDrawer._clearPolygon()
+            polygonDrawer.drawingPolygon = false
         }
 
         function _clearPolygon() {

src/MissionEditor/MissionEditor.qml

@@ -145,7 +145,7 @@ QGCView {
 
         onNewItemsFromVehicle: {
             fitViewportToMissionItems()
-            _currentMissionItem = _visualItems.get(0)
+            setCurrentItem(0)
         }
     }
 
@@ -172,6 +172,7 @@ QGCView {
     }
 
     function setCurrentItem(sequenceNumber) {
+        editorMap.polygonDraw.cancelPolygonEdit()
         _currentMissionItem = undefined
         for (var i=0; i<_visualItems.count; i++) {
             var visualItem = _visualItems.get(i)
@@ -554,6 +555,7 @@ QGCView {
                             onRemove: {
                                 itemDragger.clearItem()
                                 missionController.removeMissionItem(index)
+                                editorMap.polygonDraw.cancelPolygonEdit()
                             }
 
                             onInsert: {