Question: I have a Qt application wrapped up inside a DLL for plugging into 3rd party applications. When those 3rd party applications start the Qt application, the toolbar tooltips in the 3rd party applications stop working. As soon as I close the Qt application, they work again.

I recreated the problem in Visual Studio by creating a non-Qt executable (in this case an MFC MDI application with out-of-the-box settings), and a Qt Application (which I changed to a DLL). I added a menu item to the non-Qt executable, and handled the event as follows:

```
void MFCApp::OnFileLaunch()
{
   QtApp qtApp;
   qtApp.Launch();
}

```

The QtApp class doesn't expose the Qt API at all, and Launch() is implemented as follows:

```
int QtApp::Launch()
{
   int argc = 0;
   char *argv = 0;
   QApplication a(argc, &argv);
   MyMainWindow w;
   w.show();
   return a.exec();
}

```

The non-Qt application remains fully responsive while the Qt application is displayed, apart from the toolbar tooltips (and also keyboard shortcuts such as Ctrl A for Select All).

I suspect this is might be a Qt bug, but just wanted to check anyway in case it's my Launch code that's wrong.

I'm using Qt 4.5.2 by the way.

Thanks

Answer: 
( value == 0.00 )

Never gets true.
Or, it takes so many runs of the function that the it runs into, well, stack overflow :P
You should take another look at how you made your function. Right now it is not even useful, it can only ever return 0.
You could check `if (value * 0.98 == value)` instead of `if (value == 0)`. This condition will be met exactly when `value` becomes so small (subnormal) that it has too few bits of precision for multiplication by `0.98` to yield a different result.