title: Net tasks called using BeginInvoke on the main form not executing
body: <p>I've used Visual Studio 2013 to build a C# application with a single form, and the application has two routines that update the screen.  The routines that update the screen need to run on the main thread, so my own threads (which don't interact with the screen) call the BeginInvoke method on the main form when updates are required.  However, something is happening somewhere in the application with the result that the two update routines stop executing.  I've put logging into the app to track the calls to BeginInvoke and the execution of the update routines, and I can see that when this problem occurs, the BeginInvoke calls are made, but then nothing.  When this happens, the whole application seems to freeze.  I can't think of what might be causing this.  How can I debug this?  Is there any way of looking at what's queued to run on the main thread?  When I run in debug and break into the application, all threads look normal, and the main thread doesn't appear to be doing anything, so why isn't it processing my pending update tasks?</p>