Merge pull request #5262 from MDoerner/MakeUiDispatcherMoreDeadlockSafe

Make the UI dispatcher more deadlock safe

Author: bclothier

Rubberduck.Parsing/UIContext/UiDispatcher.cs

@@ -126,6 +126,12 @@ public Task StartTask(Action action, CancellationToken token, TaskCreationOption
         {
             CheckInitialization();
 
+            if (_contextProvider.UiContext == SynchronizationContext.Current)
+            {
+                action.Invoke();
+                return Task.CompletedTask;
+            }
+
             return Task.Factory.StartNew(action, token, options, _contextProvider.UiTaskScheduler);
         }
 
@@ -141,6 +147,12 @@ public Task<T> StartTask<T>(Func<T> func, CancellationToken token, TaskCreationO
         {
             CheckInitialization();
 
+            if (_contextProvider.UiContext == SynchronizationContext.Current)
+            {
+                var returnValue = func();
+                return Task.FromResult(returnValue);
+            }
+
             return Task.Factory.StartNew(func, token, options, _contextProvider.UiTaskScheduler);
         }