minor operation progress UI change

lib/widgets/common/action_mixins/feedback.dart

@@ -72,6 +72,9 @@ class _ReportOverlayState<T> extends State<ReportOverlay<T>> with SingleTickerPr
 
   Stream<T> get opStream => widget.opStream;
 
+  static const radius = 160.0;
+  static const strokeWidth = 16.0;
+
   @override
   void initState() {
     super.initState();
@@ -104,6 +107,7 @@ class _ReportOverlayState<T> extends State<ReportOverlay<T>> with SingleTickerPr
 
   @override
   Widget build(BuildContext context) {
+    final progressColor = Theme.of(context).accentColor;
     return AbsorbPointer(
       child: StreamBuilder<T>(
         stream: opStream,
@@ -124,20 +128,34 @@ class _ReportOverlayState<T> extends State<ReportOverlay<T>> with SingleTickerPr
                 ),
               ),
               child: Center(
-                  child: CircularPercentIndicator(
+                child: Stack(
+                  children: [
+                    Container(
+                      width: radius,
+                      height: radius,
+                      padding: const EdgeInsets.all(strokeWidth / 2),
+                      child: CircularProgressIndicator(
+                        color: progressColor.withOpacity(.1),
+                        strokeWidth: strokeWidth,
+                      ),
+                    ),
+                    CircularPercentIndicator(
                       percent: percent,
-                    lineWidth: 16,
+                      lineWidth: strokeWidth,
-                    radius: 160,
+                      radius: radius,
                       backgroundColor: Colors.white24,
-                    progressColor: Theme.of(context).accentColor,
+                      progressColor: progressColor,
                       animation: true,
                       center: Text(NumberFormat.percentPattern().format(percent)),
                       animateFromLastPercent: true,
                     ),
+                  ],
+                ),
               ),
             ),
           );
-          }),
+        },
+      ),
     );
   }
 }