Custom NSSroller inside NSScrollView

I have a IKImageBrowserView embedded inside an NSScrollView.

I'm trying achieve scroll bars like those we can see in Lion or other apps like Sparrow and Reeder. I would like my scroll bars to go over the content.

So fare the only problem I have is that the content goes over the scroll bar instead of going under.

I know that I can play with the -tile methode of the NSScrollView to arrange the different pieces but I don't know how I can use it to my purpose.

EDIT : This is the code in my -tile :

- (void)tile
{
    [super tile];

    // We move the scroll to be just below the scrollView
    NSScroller *verticalScroller = [self verticalScroller];
    NSRect verticalScrollerFrame = [verticalScroller frame];
    verticalScrollerFrame.origin.x -= 117.0;
    [verticalScroller setFrame:verticalScrollerFrame];

    // We expand the scrollview to embrace the whole window
    NSRect scrollViewFrame = [self frame];
    scrollViewFrame.size.width = 655.0;
    [self setFrame:scrollViewFrame];

}

Here is what it looks like:

Does anyone know why the content the scroll bars go under the content view? Or have an example?

I've already looked at this topic : Overlay NSScroller over content and a lot of others without finding an answer.

Thanks for your help!

Ok I think I found the problem.

NSRect scrollViewFrame = [self frame];
scrollViewFrame.size.width = 655.0;
[self setFrame:scrollViewFrame];

In this block I'm using [self frame] to get the NSClipView contentFrame instead of [[self contentView] frame].

It should look like this.

NSRect scrollViewFrame = [[self contentView] frame];
scrollViewFrame.size.width = 655.0;
[[self contentView] setFrame:scrollViewFrame];

I havn't tried it yet but I pretty sure this is the problem.