Open Radar

 
Summary:
With overlay scrollers enabled, the standard Cocoa About panel does not center RTF/HTML credits; instead they are offset to the left.

Steps to Reproduce:
1. Make sure overlay scrollers are enabled.
2. Open Preview (as an example of an Apple app with RTF credits).

Expected Results:
"Map imagery owned by NASA…" is horizontally centered in the panel.

Actual Results:
"Map imagery owned by NASA…" is horizontally offset to the left.

Regression:
This does not occur if overlay scrollers are disabled at the time the About panel is first displayed.

Notes:

The NSTextView width does not match that of the NSClipView.

The following is a relatively robust workaround which also contains some debug logging that demonstrates the problem:

- (IBAction)orderFrontAboutPanel:(id)sender;
{
    // XXX work around bug in OS X 10.7 / 10.8 where the Credits text is not centered
    NSSet *windowsBefore = [NSSet setWithArray:[NSApp windows]];
    [NSApp orderFrontStandardAboutPanelWithOptions:nil];
     
    for (NSWindow *window in [NSApp windows]) {
        if ([windowsBefore containsObject:window])
            continue;

        for (NSView *view in [[window contentView] subviews]) {
            if (![view isKindOfClass:[NSScrollView class]])
                continue;

            NSClipView *clipView = [(NSScrollView *)view contentView];
            NSRect clipViewFrame = [clipView frame];
            NSView *documentView = [clipView documentView];
            NSRect documentViewFrame = [documentView frame];

            if (clipViewFrame.size.height != documentViewFrame.size.height)
                continue; // don't mess with a scrollable view

            if (clipViewFrame.size.width != documentViewFrame.size.width) {
                NSLog(@"%@", [view _subtreeDescription]);

                documentViewFrame.size.width = clipViewFrame.size.width;
                
                [documentView setFrame:documentViewFrame];
                NSLog(@"%@", [view _subtreeDescription]);
                break;
            }
        }
        break;
    }
}

Sample output:

2013-08-24 23:34:24.339 Shroud[99473:303] [   AF     LU ] h=--- v=&-- NSScrollView 0x101a7d260 f=(12,40,260,36) b=(-) TIME drawRect: min/mean/max 0.00/0.00/0.00 ms
  [   AF  G  LU ] h=--- v=--- NSClipView 0x101a7df30 f=(0,0,260,36) b=(15,0,-,-) TIME drawRect: min/mean/max 0.00/0.00/0.00 ms
    [   AF  G  LU ] h=-&- v=-&- NSTextView 0x101a7f160 f=(0,0,275,36) b=(-) TIME drawRect: min/mean/max 0.00/0.00/0.00 ms
  [  HAF     LU#] h=--- v=--- NSScroller 0x101a83f10 f=(-100,-100,16,54) b=(-) TIME drawRect: min/mean/max 0.00/0.00/0.00 ms
  [  HAF     LU#] h=--- v=--- NSScroller 0x101a84230 f=(-100,-100,87,18) b=(-) TIME drawRect: min/mean/max 0.00/0.00/0.00 ms
A=autoresizesSubviews, C=canDrawConcurrently, D=needsDisplay, F=flipped, G=gstate, H=hidden (h=by ancestor), L=needsLayout (l=child needsLayout), U=needsUpdateConstraints (u=child needsUpdateConstraints), O=opaque, P=preservesContentDuringLiveResize, S=scaled/rotated, W=wantsLayer (w=ancestor wantsLayer), #=has surface
2013-08-24 23:34:24.340 Shroud[99473:303] [ D AF     LU ] h=--- v=&-- NSScrollView 0x101a7d260 f=(12,40,260,36) b=(-) TIME drawRect: min/mean/max 0.00/0.00/0.00 ms
  [ D AF  G  LU ] h=--- v=--- NSClipView 0x101a7df30 f=(0,0,260,36) b=(-) TIME drawRect: min/mean/max 0.00/0.00/0.00 ms
    [ D AF  G  LU ] h=-&- v=-&- NSTextView 0x101a7f160 f=(0,0,260,36) b=(-) TIME drawRect: min/mean/max 0.00/0.00/0.00 ms
  [  HAF     LU#] h=--- v=--- NSScroller 0x101a83f10 f=(-100,-100,16,54) b=(-) TIME drawRect: min/mean/max 0.00/0.00/0.00 ms
  [  HAF     LU#] h=--- v=--- NSScroller 0x101a84230 f=(-100,-100,87,18) b=(-) TIME drawRect: min/mean/max 0.00/0.00/0.00 ms
A=autoresizesSubviews, C=canDrawConcurrently, D=needsDisplay, F=flipped, G=gstate, H=hidden (h=by ancestor), L=needsLayout (l=child needsLayout), U=needsUpdateConstraints (u=child needsUpdateConstraints), O=opaque, P=preservesContentDuringLiveResize, S=scaled/rotated, W=wantsLayer (w=ancestor wantsLayer), #=has surface