Cannot intercept mouseUp mouseDown events

I'm an experienced Windows C/C++/C# programmer just getting into Cocoa/XCode.  I have read through the Cocoa Event-Handling Guide and Googled many many hours for code examples and explanations, but I still can't get the code working to intercept mouse events (mouseUp/Down/Dragged/Moved).   I've attempted to override acceptsFirstResponder and becomeFirstResponder as specified in numerous places to no avail. I know there's one last little detail that I'm missing, but I can't find it.

Below is the source code for an extremely simple project called MouseTest, whose only function is to react to mouseDown.  The main window contains a single Image Well.  The code seems to follow all of the documentation for intercepting mouse events, but nothing happens.

Any help will be greatly appreciated.

Note: Contents of source files shown below are separated by lines of //===============================================

// FILE MouseTest-Info.plist

<?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>CFBundleDevelopmentRegion</key>
    <string>English</string>
    <key>CFBundleExecutable</key>
    <string>${EXECUTABLE_NAME}</string>
    <key>CFBundleIconFile</key>
    <string></string>
    <key>CFBundleIdentifier</key>
    <string>com.yourcompany.${PRODUCT_NAME:rfc1034identifier}</string>
    <key>CFBundleInfoDictionaryVersion</key>
    <string>6.0</string>
    <key>CFBundleName</key>
    <string>${PRODUCT_NAME}</string>
    <key>CFBundlePackageType</key>
    <string>APPL</string>
    <key>CFBundleShortVersionString</key>
    <string>1.0</string>
    <key>CFBundleSignature</key>
    <string>????</string>
    <key>CFBundleVersion</key>
    <string>1</string>
    <key>LSMinimumSystemVersion</key>
    <string>${MACOSX_DEPLOYMENT_TARGET}</string>
    <key>NSMainNibFile</key>
    <string>MainMenu</string>
    <key>NSPrincipalClass</key>
    <string>NSApplication</string>
</dict>
</plist>

//===========================================================================
// FILE  MouseTestAppDelegate.h

#import <Cocoa/Cocoa.h>

@interface MouseTestAppDelegate : NSObject <NSApplicationDelegate> {
    NSWindow *window;
}

@property (assign) IBOutlet NSWindow *window;

@end

//===========================================================================
//  FILE MouseTestAppDelegate.m

#import "MouseTestAppDelegate.h"

@implementation MouseTestAppDelegate

@synthesize window;

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    // Insert code here to initialize your application
}

@end

//===========================================================================
//  FILE main.m

#import <Cocoa/Cocoa.h>

int main(int argc, char *argv[])
{
    return NSApplicationMain(argc,  (const char **) argv);
}

//===========================================================================
//  FILE MouseTest.h
#import <Cocoa/Cocoa.h>
#import <AppKit/AppKit.h>

@interface MouseTest : NSView {

}
@end

//===========================================================================
//
// FILE MouseTest.m

#import "MouseTest.h"

@implementation MouseTest

- (BOOL)acceptsFirstResponder
{
    return YES;
}

- (BOOL)becomeFirstResponder
{
    return YES;
}

- (void)mouseDown:(NSEvent *)e
{
    NSRunAlertPanel(@"TEST", @"MouseDown",@"OK", nil, nil);
}

@end