Index: Form.cs
===================================================================
--- Form.cs	(revision 134516)
+++ Form.cs	(working copy)
@@ -666,6 +666,22 @@
 				if (control_box != value) {
 					control_box = value;
 					UpdateStyles();
+
+                    if (!this.control_box) // need to check for situation where window title bar may be appearing or disappearing depending on Text property...
+                    {
+                        // Copied below from FormBorderStyle_Get
+                        Size current_client_size = ClientSize;
+                        
+                        if (this.IsHandleCreated)
+                        {
+                            this.Size = InternalSizeFromClientSize(current_client_size);
+                            XplatUI.InvalidateNC(this.Handle);
+                        }
+                        else if (is_clientsize_set)
+                        {
+                            this.Size = InternalSizeFromClientSize(current_client_size);
+                        }
+                    }
 				}
 			}
 		}
@@ -2230,6 +2246,24 @@
 
 			if (mdi_container != null)
 				mdi_container.SetParentText(true);
+
+
+            if (!this.control_box) // need to check for situation where window title bar may be appearing or disappearing...
+            {
+                // Copied below from FormBorderStyle_Get
+                Size current_client_size = ClientSize;
+                UpdateStyles();
+
+                if (this.IsHandleCreated)
+                {
+                    this.Size = InternalSizeFromClientSize(current_client_size);
+                    XplatUI.InvalidateNC(this.Handle);
+                }
+                else if (is_clientsize_set)
+                {
+                    this.Size = InternalSizeFromClientSize(current_client_size);
+                }
+            }
 		}
 
 		[EditorBrowsable(EditorBrowsableState.Advanced)]