Bug969: Just disable pause during scrub. It does not make sense.

src/AudioIO.h

@@ -168,6 +168,8 @@ class AUDACITY_DLL_API AudioIO {
    void SeekStream(double seconds) { mSeek = seconds; }
 
 #ifdef EXPERIMENTAL_SCRUBBING_SUPPORT
+   bool IsScrubbing() { return IsBusy() && mScrubQueue != 0; }
+
    static double GetMaxScrubSpeed() { return 32.0; } // Is five octaves enough for your amusement?
    static double GetMinScrubSpeed() { return 0.01; }
    /** \brief enqueue a new end time, using the last end as the new start,