Bug 855 - Data loss sample editing (Do/Undo)

I've added code that now treats sample editing as another kind of mouse capturing activity (IsAdjustingSample).  We will now not undo or redo whilst mouse is captured.  Does not depend on what key binding is used for redo/undo.

src/Menus.cpp

@@ -3503,6 +3503,10 @@ void AudacityProject::OnRedo()
       wxMessageBox(_("Nothing to redo"));
       return;
    }
+   // Can't redo whilst dragging
+   if (mTrackPanel->IsMouseCaptured()) {
+      return;
+   }
 
    TrackList *l = mUndoManager.Redo(&mViewInfo.selectedRegion);
    PopState(l);

src/TrackPanel.cpp

@@ -1578,6 +1578,7 @@ void TrackPanel::HandleEscapeKey()
       break;
    case IsZooming:
    case IsVZooming:
+   case IsAdjustingSample:
       break;
    case IsResizing:
       mCapturedTrack->SetHeight(mInitialActualHeight);
@@ -4906,6 +4907,7 @@ void TrackPanel::HandleSampleEditingClick( wxMouseEvent & event )
          ReleaseMouse();
       return;
    }
+   SetCapturedTrack( t, IsAdjustingSample);
 
    /// \todo Should mCapturedTrack take the place of mDrawingTrack??
    mDrawingTrack = t;
@@ -5149,7 +5151,7 @@ void TrackPanel::HandleSampleEditingButtonUp( wxMouseEvent & WXUNUSED(event))
    //*************************************************
    //***    UP-CLICK  (Finish drawing)             ***
    //*************************************************
-
+   SetCapturedTrack( NULL );
    //On up-click, send the state to the undo stack
    mDrawingTrack=NULL;       //Set this to NULL so it will catch improper drag events.
    MakeParentPushState(_("Moved Sample"),

src/TrackPanel.h

@@ -746,6 +746,7 @@ protected:
       IsClosing,
       IsSelecting,
       IsAdjustingLabel,
+      IsAdjustingSample,
       IsResizing,
       IsResizingBetweenLinkedTracks,
       IsResizingBelowLinkedTracks,