[Audacity-devel] UndoManager::ModifyState and why it does that

[Leland <le...@au...>]

So, while looking into a critter report, I was tracing through the 
ModifyState() function and I got to wondering...

Why does it copy the entire tracklist for EVERY little state change?  
And if I'm looking at this correctly, it is copying the exact same list 
every time.  Shouldn't that be relegated to the PushState() function 
when the track data actually changes (like when applying an effect)?

I look at ModifyState() as a function that should update the currently 
active undo stack object with items like current selection, track 
selection state...well, basically anything that doesn't monkey with the 
track data itself...like this stuff:

    mSelected = orig.mSelected;
    mLinked = orig.mLinked;
    mMute = orig.mMute;
    mSolo = orig.mSolo;
    mHeight = orig.mHeight;
    mMinimized = orig.mMinimized;
    mChannel = orig.mChannel;
    mFormat = orig.mFormat;
    mRate = orig.mRate;
    mGain = orig.mGain;
    mPan = orig.mPan;
    SetDefaultName(orig.GetDefaultName());
    SetName(orig.GetName());
    mDisplay = orig.mDisplay;
    mDisplayMin = orig.mDisplayMin;
    mDisplayMax = orig.mDisplayMax;
    mDisplayNumLocations = 0;
    mDisplayLocations = NULL;
    mDisplayNumLocationsAllocated = 0;

Anyway, just thought I'd start the discussion as it seems like a simple 
way to (possibly) improve responsiveness.