Right ALT key not recognized

[papillon]

I have the following keypress event routine (Qt 4.7):

void GLTerrain::keyPressEvent(QKeyEvent *event)
{
switch (event->key()) {
		case Qt::Key_Shift:
			bShift=true;
			break;
		case Qt::Key_Alt:
			bAlt=true;
			if (bEnableAllBoundingBoxFeature==true)	bAllBoundingBox=true;
			break;
}

void GLTerrain::keyPressEvent(QKeyEvent *event)
{
switch (event->key()) {
		case Qt::Key_Shift:
			bShift=true;
			break;
		case Qt::Key_Alt:
			bAlt=true;
			if (bEnableAllBoundingBoxFeature==true)	bAllBoundingBox=true;
			break;
}

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On OSX everything works fine, on Windows (VC++ 2008, 64bit), the right ALT key event is not triggered (only the left ALT is).
Any idea? Thanks