如何检测nsdrawer是否会在屏幕外打开

我正在开发一个主窗口有一个nsdrawer的应用程序。抽屉总是在右边打开,这是至关重要的,这就是我编码它的工作方式。我想知道的是,是否有一种方法来检测抽屉是否会“离开屏幕”…有什么方法可以检测到这个吗?如果是这样,怎么办?另外,如何移动主窗口来调整将打开的抽屉的宽度?

事先谢谢。

尼克

编辑:

这是罗布建议的解决办法。

-(IBAction)toggleDrawer:(id)sender
{

NSRect screenFrame = [[[NSScreen screens] objectAtIndex:0] visibleFrame];
NSRect windowFrame = [window frame];
NSRect drawerFrame = [[[drawer contentView] window] frame];

if ([drawer state] == NSDrawerOpenState)
{
    [drawer close];
}
else
{
    if (windowFrame.size.width + 
        windowFrame.origin.x +
        drawerFrame.size.width > screenFrame.size.width)
    {
        NSLog(@"Will Open Off Screen");

        float offset = (windowFrame.size.width + 
                    windowFrame.origin.x + 
                    drawerFrame.size.width) - screenFrame.size.width;

        NSRect newRect = NSMakeRect(windowFrame.origin.x - offset, 
                                            windowFrame.origin.y,
                                            windowFrame.size.width,
                                            windowFrame.size.height);

        [window setFrame:newRect display:YES animate:YES];
    }

    [drawer openOnEdge:NSMaxXEdge];     
}
}