Tooltips are not shown for QGraphicsProxyWidget [regression]

Function
Event System
Version
4.6.0-beta
Platform
Linux
Platform details
Qt 4.6-stable from git using nightly snapshots
Compilers
GCC
Compiler details
uname -a
Linux segfault 2.6.32-rc4-custom #3 SMP Mon Oct 12 17:55:10 EDT 2009 x86_64 GNU/Linux
spstarr@segfault:~$ gcc -v
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.4.1-4ubuntu7' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c+,fortran,objc,obj-c+ --prefix=/usr --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --program-suffix=-4.4 --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-mpfr --enable-objc-gc --disable-werror --with-arch-32=i486 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.4.1 (Ubuntu 4.4.1-4ubuntu7)

Steps to reproduce / test case
When using QGraphicsProxyWidegt, Qt 4.6 no longer repsonds to helpEvent() so no tooltips are being displayed from any widget.

Example code below will show the tooltip will not pop up.

#include <QtGui> 

int main(int argc, char *argv[]) 
{ 
    QApplication app(argc, argv); 
    
    QTextEdit *edit = new QTextEdit; 
    edit->setHtml("Hei!"); 
    edit->setWordWrapMode(QTextOption::NoWrap); 
    edit->setTextBackgroundColor(Qt::white); 
    edit->setTextColor(Qt::blue); 
    edit->setToolTip("ToolTip in original widget - where am I?");

#ifdef dontshow
    edit->show();
#else
    QGraphicsProxyWidget *widget = new QGraphicsProxyWidget;
    widget->setWidget(edit);
    widget->show();
    widget->setToolTip("This ToolTip shows instead?");
    QGraphicsLinearLayout *layout = new QGraphicsLinearLayout;
    layout->addItem(widget);

    QGraphicsWidget *window = new QGraphicsWidget(0, Qt::Window);
    window->setLayout(layout);

    QGraphicsScene scene;
    scene.addItem(window);

    QGraphicsView view(&scene);
    view.show();
#endif

    return app.exec(); 
}