If there is no header view, there should be no corner view. This is what Cocoa does. Also for correctness -enclosingScrollView should be used to get the table's scrollview. Test app included.

AppKit/CPTableView.j

@@ -1470,7 +1470,7 @@ NOT YET IMPLEMENTED
 
     _cornerView = aView;
 
-    var scrollView = [[self superview] superview];
+    var scrollView = [self enclosingScrollView];
 
     if ([scrollView isKindOfClass:[CPScrollView class]] && [scrollView documentView] === self)
         [scrollView _updateCornerAndHeaderView];
@@ -1506,8 +1506,14 @@ NOT YET IMPLEMENTED
         [_headerView setTableView:self];
         [_headerView setFrameSize:_CGSizeMake(_CGRectGetWidth([self frame]), _CGRectGetHeight([_headerView frame]))];
     }
+    else
+    {
+        // If there is no header view, there should be no corner view
+        [_cornerView removeFromSuperview];
+        _cornerView = nil;
+    }
 
-    var scrollView = [[self superview] superview];
+    var scrollView = [self enclosingScrollView];
 
     if ([scrollView isKindOfClass:[CPScrollView class]] && [scrollView documentView] === self)
         [scrollView _updateCornerAndHeaderView];

Tests/Manual/TableTest/HeaderView-CornerView/AppController.j

@@ -0,0 +1,115 @@
+/*
+ * AppController.j
+ * HeaderView-CornerView
+ *
+ * Created by aparajita on May 18, 2011.
+ * Copyright 2011, Victory-Heart Productions All rights reserved.
+ */
+
+@import <Foundation/CPObject.j>
+
+var brokenTable = nil,
+    fixedTable = nil;
+
+@implementation AppController : CPObject
+{
+    CPWindow theWindow;
+}
+
+- (void)applicationDidFinishLaunching:(CPNotification)aNotification
+{    
+    theWindow = [[CPWindow alloc] initWithContentRect:CGRectMakeZero() styleMask:CPBorderlessBridgeWindowMask];
+            
+    brokenTable = [self makeTableWithCaption:@"No header, has corner: wrong" at:CPPointMake(50, 50)];
+    fixedTable = [self makeTableWithCaption:@"No header, no corner: correct" at:CPPointMake(250, 50)];
+
+    [brokenTable setHeaderView:nil];
+    [fixedTable setHeaderView:nil];
+
+    [theWindow orderFront:self];
+
+    // Uncomment the following line to turn on the standard menu bar.
+    //[CPMenu setMenuBarVisible:YES];
+}
+
+- (void)makeTableWithCaption:(CPString)caption at:(CGPoint)location
+{
+    var label = [CPTextField labelWithTitle:caption],
+        table = [[CPTableView alloc] initWithFrame:CGRectMakeZero()],
+        frame = CGRectMake(location.x, location.y + 25, 150, ([table rowHeight] * 5) + 2),
+        scroll = [[CPScrollView alloc] initWithFrame:frame];
+
+    [label setFrameOrigin:CGPointMake(location.x, location.y)];
+    
+    [table setDataSource:self];
+    [table setDelegate:self];
+    [table setColumnAutoresizingStyle:CPTableViewLastColumnOnlyAutoresizingStyle];
+    [table setUsesAlternatingRowBackgroundColors:YES];
+    [table setAllowsMultipleSelection:NO];
+    [table setIntercellSpacing:CGSizeMake(0, 0)];
+
+    var column = [[CPTableColumn alloc] initWithIdentifier:"1"];
+
+    [column setWidth:CGRectGetWidth(frame) - [CPScroller scrollerWidth]];
+    [column setResizingMask:CPTableColumnNoResizing];
+    [table addTableColumn:column];
+    [table selectRowIndexes:[CPIndexSet indexSetWithIndex:0] byExtendingSelection:NO];
+
+    [scroll setBorderType:CPLineBorder];
+    [scroll setHasHorizontalScroller:NO];
+    [scroll setDocumentView:table];
+    
+    var contentView = [theWindow contentView];
+    
+    [contentView addSubview:label];
+    [contentView addSubview:scroll];
+    
+    return table;
+}
+
+/*!
+    Returns the number of rows in the table data.
+    The default implementation returns the size of the table data array.
+*/
+- (int)numberOfRowsInTableView:(id)tableView
+{
+    return 10;
+}
+
+- (id)tableView:(id)tableView objectValueForTableColumn:(CPTableColumn)aColumn row:(int)aRow
+{
+    return @"Row " + aRow;
+}
+
+@end
+
+@implementation CPTableView (test)
+
+- (void)setHeaderView:(CPView)aHeaderView
+{
+    if (_headerView === aHeaderView)
+        return;
+
+    [_headerView setTableView:nil];
+
+    _headerView = aHeaderView;
+
+    if (_headerView)
+    {
+        [_headerView setTableView:self];
+        [_headerView setFrameSize:CGSizeMake(CGRectGetWidth([self frame]), CGRectGetHeight([_headerView frame]))];
+    }
+    else if (self === fixedTable)
+    {
+        // If there is no header view, there should be no corner view
+        [_cornerView removeFromSuperview];
+        _cornerView = nil;
+    }
+
+    var scrollView = [self enclosingScrollView];
+
+    if ([scrollView isKindOfClass:[CPScrollView class]] && [scrollView documentView] === self)
+        [scrollView _updateCornerAndHeaderView];
+}
+
+@end

Tests/Manual/TableTest/HeaderView-CornerView/Info.plist

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CPApplicationDelegateClass</key>
+	<string>AppController</string>
+	<key>CPBundleName</key>
+	<string>HeaderView-CornerView</string>
+	<key>CPPrincipalClass</key>
+	<string>CPApplication</string>
+</dict>
+</plist>

Tests/Manual/TableTest/HeaderView-CornerView/Jakefile

@@ -0,0 +1,93 @@
+/*
+ * Jakefile
+ * HeaderView-CornerView
+ *
+ * Created by aparajita on May 18, 2011.
+ * Copyright 2011, Victory-Heart Productions All rights reserved.
+ */
+
+var ENV = require("system").env,
+    FILE = require("file"),
+    JAKE = require("jake"),
+    task = JAKE.task,
+    FileList = JAKE.FileList,
+    app = require("cappuccino/jake").app,
+    configuration = ENV["CONFIG"] || ENV["CONFIGURATION"] || ENV["c"] || "Debug",
+    OS = require("os");
+
+app ("HeaderViewCornerView", function(task)
+{
+    task.setBuildIntermediatesPath(FILE.join("Build", "HeaderViewCornerView.build", configuration));
+    task.setBuildPath(FILE.join("Build", configuration));
+
+    task.setProductName("HeaderView-CornerView");
+    task.setIdentifier("com.aparajita.HeaderViewCornerView");
+    task.setVersion("1.0");
+    task.setAuthor("Victory-Heart Productions");
+    task.setEmail("feedback @nospam@ yourcompany.com");
+    task.setSummary("HeaderView-CornerView");
+    task.setSources((new FileList("**/*.j")).exclude(FILE.join("Build", "**")));
+    task.setResources(new FileList("Resources/**"));
+    task.setIndexFilePath("index.html");
+    task.setInfoPlistPath("Info.plist");
+
+    if (configuration === "Debug")
+        task.setCompilerFlags("-DDEBUG -g");
+    else
+        task.setCompilerFlags("-O");
+});
+
+task ("default", ["HeaderViewCornerView"], function()
+{
+    printResults(configuration);
+});
+
+task ("build", ["default"]);
+
+task ("debug", function()
+{
+    ENV["CONFIGURATION"] = "Debug";
+    JAKE.subjake(["."], "build", ENV);
+});
+
+task ("release", function()
+{
+    ENV["CONFIGURATION"] = "Release";
+    JAKE.subjake(["."], "build", ENV);
+});
+
+task ("run", ["debug"], function()
+{
+    OS.system(["open", FILE.join("Build", "Debug", "HeaderViewCornerView", "index.html")]);
+});
+
+task ("run-release", ["release"], function()
+{
+    OS.system(["open", FILE.join("Build", "Release", "HeaderViewCornerView", "index.html")]);
+});
+
+task ("deploy", ["release"], function()
+{
+    FILE.mkdirs(FILE.join("Build", "Deployment", "HeaderViewCornerView"));
+    OS.system(["press", "-f", FILE.join("Build", "Release", "HeaderViewCornerView"), FILE.join("Build", "Deployment", "HeaderViewCornerView")]);
+    printResults("Deployment")
+});
+
+task ("desktop", ["release"], function()
+{
+    FILE.mkdirs(FILE.join("Build", "Desktop", "HeaderViewCornerView"));
+    require("cappuccino/nativehost").buildNativeHost(FILE.join("Build", "Release", "HeaderViewCornerView"), FILE.join("Build", "Desktop", "HeaderViewCornerView", "HeaderViewCornerView.app"));
+    printResults("Desktop")
+});
+
+task ("run-desktop", ["desktop"], function()
+{
+    OS.system([FILE.join("Build", "Desktop", "HeaderViewCornerView", "HeaderViewCornerView.app", "Contents", "MacOS", "NativeHost"), "-i"]);
+});
+
+function printResults(configuration)
+{
+    print("----------------------------");
+    print(configuration+" app built at path: "+FILE.join("Build", configuration, "HeaderViewCornerView"));
+    print("----------------------------");
+}

Tests/Manual/TableTest/HeaderView-CornerView/index-debug.html

@@ -0,0 +1,103 @@
+<!DOCTYPE html
+    PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
+<!--
+ index-debug.html
+ HeaderView-CornerView
+
+ Created by aparajita on May 18, 2011.
+ Copyright 2011, Victory-Heart Productions All rights reserved.
+-->
+    <head>
+        <meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7, chrome=1" />
+
+        <meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
+
+        <meta name="apple-mobile-web-app-capable" content="yes" />
+        <meta name="apple-mobile-web-app-status-bar-style" content="black" />
+
+        <link rel="apple-touch-icon" href="Resources/icon.png" />
+        <link rel="apple-touch-startup-image" href="Resources/default.png" />
+
+        <title>HeaderView-CornerView</title>
+
+        <script type="text/javascript">
+            OBJJ_MAIN_FILE = "main.j";
+            OBJJ_INCLUDE_PATHS = ["Frameworks/Debug", "Frameworks", "SomethingElse"];
+        </script>
+
+        <script src="Frameworks/Debug/Objective-J/Objective-J.js" type="text/javascript" charset="UTF-8"></script>
+
+        <script type="text/javascript">
+            objj_msgSend_reset();
+
+            // DEBUG OPTIONS:
+
+            // Uncomment to enable printing of backtraces on exceptions:
+            //objj_msgSend_decorate(objj_backtrace_decorator);
+
+            // Uncomment to supress exceptions that take place inside a message
+            //objj_msgSend_decorate(objj_supress_exceptions_decorator)
+
+            // Uncomment to enable runtime type checking:
+            //objj_msgSend_decorate(objj_typecheck_decorator);
+
+            // Uncomment (along with both above) to print backtraces on type check errors:
+            //objj_typecheck_prints_backtrace = true;
+
+            // Uncomment to disable the default logger (CPLogConsole if window.console exists, CPLogPopup otherwise):
+            //CPLogUnregister(CPLogDefault);
+
+            // Uncomment to enable a specific logger:
+            //CPLogRegister(CPLogConsole);
+            //CPLogRegister(CPLogPopup);
+        </script>
+
+        <style type="text/css">
+            body{margin:0; padding:0;}
+            #container {position: absolute; top:50%; left:50%;}
+            #content {width:800px; text-align:center; margin-left: -400px; height:50px; margin-top:-25px; line-height: 50px;}
+            #content {font-family: "Helvetica", "Arial", sans-serif; font-size: 18px; color: black; text-shadow: 0px 1px 0px white; }
+            #loadgraphic {margin-right: 0.2em; margin-bottom:-2px;}
+        </style>
+
+        <!--[if lt IE 7]>
+        <STYLE type="text/css">
+            #container { position: relative; top: 50%; }
+            #content { position: relative;}
+        </STYLE>
+        <![endif]-->
+
+    </head>
+
+    <body style="">
+        <div id="cappuccino-body">
+            <div id="loadingcontainer" style="background-color: #eeeeee; overflow:hidden; width:100%; height:100%; position: absolute; top: 0; left: 0;">
+                <script type="text/javascript">
+                    document.write("<div id='container'><p id='content'>" +
+                                   "<img id='loadgraphic' width='16' height='16' src='Resources/spinner.gif' /> " +
+                                   "Loading HeaderView-CornerView...</p></div>");
+                </script>
+
+                <noscript>
+                    <div id="container">
+                        <div style="width: 440px; padding: 10px 25px 20px 25px; font-family: sans-serif; background-color: #ffffff; position: relative; left: -245px; top: -120px; text-align: center; -moz-border-radius: 20px; -webkit-border-radius: 20px; color: #555555">
+                            <p style="line-height: 1.4em;">JavaScript is required for this site to work correctly but is either disabled or not supported by your browser.</p>
+                            <p style="font-size:120%; padding:10px;"><a href="http://cappuccino.org/noscript">Show me how to enable JavaScript</a></p>
+                            <p style="font-size:80%;">You may want to upgrade to a newer browser while you're at it:</p>
+                            <ul style="margin:0;padding:0; text-align: center; font-size:80%;" >
+                                <li style="display: inline;"><a href="http://www.apple.com/safari/download/">Safari</a></li>
+                                <li style="display: inline;"><a href="http://www.mozilla.com/en-US/firefox/">Firefox</a></li>
+                                <li style="display: inline;"><a href="http://www.google.com/chrome/">Chrome</a></li>
+                                <li style="display: inline;"><a href="http://www.opera.com/download/">Opera</a></li>
+                                <li style="display: inline;"><a href="http://www.microsoft.com/windows/downloads/ie/getitnow.mspx">Internet Explorer</a></li>
+                            </ul>
+                        </div>
+                    </div>
+                </noscript>
+            </div>
+        </div>
+    </body>
+
+</html>

Tests/Manual/TableTest/HeaderView-CornerView/index.html

@@ -0,0 +1,78 @@
+<!DOCTYPE html
+    PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
+<!--
+ index.html
+ HeaderView-CornerView
+
+ Created by aparajita on May 18, 2011.
+ Copyright 2011, Victory-Heart Productions All rights reserved.
+-->
+    <head>
+        <meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7, chrome=1" />
+
+        <meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
+
+        <meta name="apple-mobile-web-app-capable" content="yes" />
+        <meta name="apple-mobile-web-app-status-bar-style" content="black" />
+
+        <link rel="apple-touch-icon" href="Resources/icon.png" />
+        <link rel="apple-touch-startup-image" href="Resources/default.png" />
+
+        <title>HeaderView-CornerView</title>
+
+        <script type="text/javascript">
+            OBJJ_MAIN_FILE = "main.j";
+        </script>
+
+        <script type="text/javascript" src="Frameworks/Objective-J/Objective-J.js" charset="UTF-8"></script>
+
+        <style type="text/css">
+            body{margin:0; padding:0;}
+            #container {position: absolute; top:50%; left:50%;}
+            #content {width:800px; text-align:center; margin-left: -400px; height:50px; margin-top:-25px; line-height: 50px;}
+            #content {font-family: "Helvetica", "Arial", sans-serif; font-size: 18px; color: black; text-shadow: 0px 1px 0px white; }
+            #loadgraphic {margin-right: 0.2em; margin-bottom:-2px;}
+        </style>
+
+        <!--[if lt IE 7]>
+        <STYLE type="text/css">
+            #container { position: relative; top: 50%; }
+            #content { position: relative;}
+        </STYLE>
+        <![endif]-->
+
+    </head>
+
+    <body style="">
+        <div id="cappuccino-body">
+            <div id="loadingcontainer" style="background-color: #eeeeee; overflow:hidden; width:100%; height:100%; position: absolute; top: 0; left: 0;">
+                <script type="text/javascript">
+                    document.write("<div id='container'><p id='content'>" +
+                                   "<img id='loadgraphic' width='16' height='16' src='Resources/spinner.gif' /> " +
+                                   "Loading HeaderView-CornerView...</p></div>");
+                </script>
+
+                <noscript>
+                    <div id="container">
+                        <div style="width: 440px; padding: 10px 25px 20px 25px; font-family: sans-serif; background-color: #ffffff; position: relative; left: -245px; top: -120px; text-align: center; -moz-border-radius: 20px; -webkit-border-radius: 20px; color: #555555">
+                            <p style="line-height: 1.4em;">JavaScript is required for this site to work correctly but is either disabled or not supported by your browser.</p>
+                            <p style="font-size:120%; padding:10px;"><a href="http://cappuccino.org/noscript">Show me how to enable JavaScript</a></p>
+                            <p style="font-size:80%;">You may want to upgrade to a newer browser while you're at it:</p>
+                            <ul style="margin:0;padding:0; text-align: center; font-size:80%;" >
+                                <li style="display: inline;"><a href="http://www.apple.com/safari/download/">Safari</a></li>
+                                <li style="display: inline;"><a href="http://www.mozilla.com/en-US/firefox/">Firefox</a></li>
+                                <li style="display: inline;"><a href="http://www.google.com/chrome/">Chrome</a></li>
+                                <li style="display: inline;"><a href="http://www.opera.com/download/">Opera</a></li>
+                                <li style="display: inline;"><a href="http://www.microsoft.com/windows/downloads/ie/getitnow.mspx">Internet Explorer</a></li>
+                            </ul>
+                        </div>
+                    </div>
+                </noscript>
+            </div>
+        </div>
+    </body>
+
+</html>
+

Tests/Manual/TableTest/HeaderView-CornerView/main.j

@@ -0,0 +1,18 @@
+/*
+ * AppController.j
+ * HeaderView-CornerView
+ *
+ * Created by aparajita on May 18, 2011.
+ * Copyright 2011, Victory-Heart Productions All rights reserved.
+ */
+
+@import <Foundation/Foundation.j>
+@import <AppKit/AppKit.j>
+
+@import "AppController.j"
+
+
+function main(args, namedArgs)
+{
+    CPApplicationMain(args, namedArgs);
+}