Do not force control to create its handle in Resize event (the designer places code that raises this event before the rest of the events are hooked). Instead, suppress the event and raise it once the handle is actually created.

Source/GLControl/GLControl.cs

@@ -51,6 +51,11 @@ namespace OpenTK
         int major, minor;
         GraphicsContextFlags flags;
         bool? initial_vsync_value;
+        // Indicates that OnResize was called before OnHandleCreated.
+        // To avoid issues with missing OpenGL contexts, we suppress
+        // the premature Resize event and raise it as soon as the handle
+        // is ready.
+        bool resize_event_suppressed;
 
         #region --- Constructors ---
 
@@ -153,6 +158,12 @@ namespace OpenTK
             }
 
             base.OnHandleCreated(e);
+
+            if (resize_event_suppressed)
+            {
+                OnResize(EventArgs.Empty);
+                resize_event_suppressed = false;
+            }
         }
 
         /// <summary>Raises the HandleDestroyed event.</summary>
@@ -190,12 +201,18 @@ namespace OpenTK
 
         /// <summary>
         /// Raises the Resize event.
+        /// Note: this method may be called before the OpenGL context is ready.
+        /// Check that IsHandleCreated is true before using any OpenGL methods.
         /// </summary>
         /// <param name="e">A System.EventArgs that contains the event data.</param>
         protected override void OnResize(EventArgs e)
         {
-            if (IsHandleCreated == false)
-                CreateHandle();
+            // Do not raise OnResize event before the handle and context are created.
+            if (!IsHandleCreated)
+            {
+                resize_event_suppressed = true;
+                return;
+            }
 
             if (context != null)
                 context.Update(Implementation.WindowInfo);