QWidget move() and QGraphicsOpacityEffect causing black border - c++

Question

This took me awhile to figure out... but whenever I try to use a QWidget's move() (or even setGeometry) function that has a child QWidgit with a QGraphicsOpacityEffect assigned to it, it causes the QWidgit to have a black border along the right and bottom sides.
The border is exactly the size of the amount of pixels that I moved. If I increase the amount I move the widget, the border increases also...
If I remove the move() call, the problem is fixed... If I use 0.99 instead of 1.0 in the setOpacity() call, it fixes the problem...
Here's a picture of the issue...
Does anyone know how to avoid/fix this...?
Here's my code.
mainwindow.ui
<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>MainWindow</class>
<widget class="QMainWindow" name="MainWindow">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>560</width>
<height>351</height>
</rect>
</property>
<property name="windowTitle">
<string>MainWindow</string>
</property>
<widget class="QWidget" name="centralWidget">
<widget class="QWidget" name="TestHolder2" native="true">
<property name="geometry">
<rect>
<x>200</x>
<y>90</y>
<width>120</width>
<height>80</height>
</rect>
</property>
</widget>
</widget>
</widget>
<layoutdefault spacing="6" margin="11"/>
<resources/>
<connections/>
</ui>
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
mainwindow.cpp
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
ui->TestHolder2->resize(450, 250);
ui->TestHolder2->move(11, 11);
ui->TestHolder2->setStyleSheet("background-color: black;");
QWidget* new_widget = new QWidget(ui->TestHolder2);
new_widget->setStyleSheet("background-color:red;");
new_widget->resize(450, 250);
QGraphicsOpacityEffect* opacity_effect = new QGraphicsOpacityEffect(new_widget);
new_widget->setGraphicsEffect(opacity_effect);
opacity_effect->setOpacity(1);
}
MainWindow::~MainWindow()
{
delete ui;
}
main.cpp
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}