Set IsExecuting back to false either after the extraction has reporte…

…d as complete or no extraction took place because there were no directories to extract from.

SubFolderExtractor/Model/ExtractionModel.cs

@@ -130,7 +130,7 @@ public void StartExtraction(string startDirectory)
                 NotifyOfPropertyChange(() => Progress);
             }
 
-            IsExecuting = false;
+            if (totalDirectoriesCount == 0) IsExecuting = false;
         }
 
         public void Cancel()
@@ -204,6 +204,8 @@ private void ExtractionFinished(object sender, EventArgs e)
 
             if (!complete)
                 autoResetEvent.Set(); // allow the next extraction to start (if there is one)
+            else
+                IsExecuting = false;
         }
 
         private void ExtractionProgress(object sender, ProgressEventArgs e)