🐛 1修复程序崩溃, :boom:2添加时钟显秒

Plugins/ShowSeconds/ViewModel/SecondsDataContext.cs

@@ -0,0 +1,25 @@
+using System.ComponentModel;
+
+
+namespace ShowSeconds.ViewModel
+{
+    public class SecondsDataContext : INotifyPropertyChanged
+    {
+        private string seconds;
+        public string Seconds
+        {
+            set
+            {
+                seconds = value;
+                OnPropertyChanged("Seconds");
+            }
+            get { return seconds; }
+        }
+
+        public event PropertyChangedEventHandler PropertyChanged;
+        private void OnPropertyChanged(string propertyName)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+}