main.cpp

#include <QApplication>
#include <QIcon>

#include "sourceedit.h"

int main(int argc, char *argv[])
{
	QApplication app(argc, argv);

	MyWidget *widget = new MyWidget(0);
	widget->resize(800,600);
	widget->show();

	return app.exec();
}


sourceedit.cpp

#include <QTextEdit>
#include <QPushButton>

#include "sourceedit.h"
#include "preferences.h"

MyWidget::MyWidget(QWidget *parent)
    : QWidget(parent)
{
	button = new QPushButton( "Optionen",this);
	connect(button, SIGNAL(clicked()), this, SLOT(showOptions()));

	edit = new QTextEdit(this);
	edit->setGeometry(10,40,width()-10, height()-10);
}

QTextEdit *MyWidget::GibZeiger()
{
	return edit;
}

void MyWidget::showOptions()
{
	MyPreferences *prefs = new MyPreferences(0);
	prefs->resize(700,400);
	prefs->show();

  // -> Hier neu
  pref->SetzeZeiger( edit )
}


sourceedit.h

#ifndef SOURCEEDIT_H
#define SOURCEEDIT_H

#include <QWidget>
#include <QTextEdit>
#include <QPushButton>

class MyWidget : public QWidget
{
	Q_OBJECT
public:
	MyWidget(QWidget *parent = 0);
public slots:
	void showOptions();
	QTextEdit *GibZeiger();

private:
	QTextEdit *edit;	
	QPushButton *button;
};

#endif


proference.cpp

#include <QPushButton>
#include <QTextEdit>

#include "preferences.h"
#include "sourceedit.h"

MyPreferences::MyPreferences(QWidget *parent)
    : QWidget(parent)
{
	okButton = new QPushButton("Apply", this);
	okButton->move(10,10);
	connect(okButton, SIGNAL(clicked()), this, SLOT(applyChanges()));

	label = new QLabel(this);
	label->setGeometry(10,70,150,30);

	edit = 0;
}

void MyPreferences::applyChanges()
{
/*	MyWidget mainclass;

	QTextEdit* Zeiger = mainclass.GibZeiger();
	SetzeZeiger( Zeiger );*/

  // -> hier neu
	TueWasMitFremdzeiger();
}

void MyPreferences::SetzeZeiger( QTextEdit* Zeiger )
{
	edit = Zeiger;

}

void MyPreferences::TueWasMitFremdzeiger()
{
	if( edit != 0 )
	{
		edit->setText("evtl funktioniert es");
		edit->selectAll();
		edit->setFontPointSize(6);
	}
}


preference.h

#ifndef PREFERENCES_H
#define PREFERENCES_H

#include <QWidget>
#include <QPushButton>
#include <QLabel>

#include "sourceedit.h"

class MyPreferences : public QWidget
{
	Q_OBJECT
public:
	MyPreferences(QWidget *parent = 0);
	
public slots:
	void applyChanges();
	void SetzeZeiger( QTextEdit* Zeiger );
	void TueWasMitFremdzeiger();

private:
	QPushButton *okButton;
	QLabel *label;
	QTextEdit *edit;

};

#endif