Don't SetCursorPosition when not Rendered.

Block the setting of the console cursor when the buffer hasn't been
completely rendered due to an input queue waiting to be processed.

Fixes #1081.

PSReadLine/Render.cs

@@ -61,6 +61,7 @@ class RenderData
         };
         private int _initialX;
         private int _initialY;
+        private bool _waitingToRender;
 
         private ConsoleColor _initialForeground;
         private ConsoleColor _initialBackground;
@@ -112,6 +113,7 @@ private void Render()
                 _tokens = null;
                 _ast = null;
                 _parseErrors = null;
+                _waitingToRender = true;
                 return;
             }
 
@@ -816,6 +818,7 @@ void UpdateColorsIfNecessary(string newColor)
             // TODO: set WindowTop if necessary
 
             _lastRenderTime.Restart();
+            _waitingToRender = false;
         }
 
         private static string Spaces(int cnt)
@@ -980,19 +983,24 @@ private void RecomputeInitialCoords()
 
         private void MoveCursor(int newCursor)
         {
-            // In case the buffer was resized
-            RecomputeInitialCoords();
-            _previousRender.bufferWidth = _console.BufferWidth;
-            _previousRender.bufferHeight = _console.BufferHeight;
-
-            var point = ConvertOffsetToPoint(newCursor);
-            if (point.Y < 0)
+            // Only update screen cursor if the buffer is fully rendered.
+            if (!_waitingToRender)
             {
-                Ding();
-                return;
+                // In case the buffer was resized
+                RecomputeInitialCoords();
+                _previousRender.bufferWidth = _console.BufferWidth;
+                _previousRender.bufferHeight = _console.BufferHeight;
+
+                var point = ConvertOffsetToPoint(newCursor);
+                if (point.Y < 0)
+                {
+                    Ding();
+                    return;
+                }
+
+                _console.SetCursorPosition(point.X, point.Y);
             }
 
-            _console.SetCursorPosition(point.X, point.Y);
             _current = newCursor;
         }