New library lib-exceptions

libraries/lib-exceptions/UserException.h

@@ -0,0 +1,26 @@
+/*!
+ @file UserException.h
+ @brief An AudacityException with no visible message
+
+ Created by Paul Licameli on 11/27/16.
+
+*/
+
+#ifndef __AUDACITY_USER_EXCEPTION__
+#define __AUDACITY_USER_EXCEPTION__
+
+#include "AudacityException.h"
+
+ //! Can be thrown when user cancels operations, as with a progress dialog.  Delayed handler does nothing
+/*! This class does not inherit from MessageBoxException. */
+class EXCEPTIONS_API UserException final : public AudacityException
+{
+public:
+   UserException() {}
+
+   ~UserException() override;
+
+   void DelayedHandlerAction() override;
+};
+
+#endif