Widget promoted to a custom widget in QtDesigner shows up blank - qt

Question

When I promote a QWidget to a custom widget in QtDesigner, everything compiles fine, but when I run the program the widget seems to be blank. I have made a very simple demo of this:
Form.h
#ifndef FORM_H
#define FORM_H
#include <QWidget>
#include "ui_form.h"
class Form : public QWidget, private Ui::Form
{
Q_OBJECT
public:
Form(QWidget *parent = 0);
};
#endif
Form.cpp
#include "form.h"
Form::Form(QWidget* parent)
: QWidget(parent)
{
setupUi(this);
}
TestWidget.h
#ifndef TestWidget_H
#define TestWidget_H
#include "ui_TestWidget.h"
#include <QMainWindow>
class TestWidget : public QWidget, private Ui::TestWidget
{
Q_OBJECT
public:
TestWidget(QWidget *parent = 0);
};
#endif
TestWidget.cpp
#include "TestWidget.h"
TestWidget::TestWidget(QWidget *parent)
: QWidget(parent)
{
}
main.cpp
#include <QApplication>
#include "form.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
Form form;
form.show();
return app.exec();
}
Form.ui
<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>Form</class>
<widget class="QWidget" name="Form">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>532</width>
<height>341</height>
</rect>
</property>
<property name="windowTitle">
<string>Form</string>
</property>
<widget class="TestWidget" name="widget" native="true">
<property name="geometry">
<rect>
<x>130</x>
<y>90</y>
<width>161</width>
<height>121</height>
</rect>
</property>
</widget>
</widget>
<customwidgets>
<customwidget>
<class>TestWidget</class>
<extends>QWidget</extends>
<header>TestWidget.h</header>
<container>1</container>
</customwidget>
</customwidgets>
<resources/>
<connections/>
</ui>
TestWidget.ui
<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>TestWidget</class>
<widget class="QWidget" name="TestWidget">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>306</width>
<height>60</height>
</rect>
</property>
<property name="windowTitle">
<string>Form</string>
</property>
<layout class="QVBoxLayout" name="verticalLayout">
<item>
<widget class="QLabel" name="label">
<property name="text">
<string>Current path:</string>
</property>
</widget>
</item>
</layout>
</widget>
<resources/>
<connections/>
</ui>
When I run this, I just see a blank widget, when I would expect to see the label with "Current path:" displayed.

Answer 1

I just needed to add
setupUi(this);
to the TestWidget constructor.

Answer 2

If I were able to comment I would put this there... need more rep still though before that is an option.
Looking at the geometry of the TestWidget I see that it is 306 pixels wide:
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
**<width>306</width>**
<height>60</height>
</rect>
</property>
In Form.ui, you're giving it only 161 pixels:
<widget class="TestWidget" name="widget" native="true">
<property name="geometry">
<rect>
<x>130</x>
<y>90</y>
**<width>161</width>**
<height>121</height>
</rect>
</property>
</widget>
Might that be part of the problem - the label is there, it is just outside of the painted area for the widget?