Hi to all,
I wrote a very simple informative dialog:

.h
Qt Code: 
  1. #ifndef __INFODLG_H__
  2. #define __INFODLG_H__
  3.  
  4. #include "GeneratedFiles/ui_infoDlg.h"
  5.  
  6. #include <QDialog>
  7.  
  8. class MainWindow;
  9. class QTimer;
  10.  
  11. class InfoDlg : public QDialog
  12. {
  13. 	Q_OBJECT
  14.  
  15. public:
  16. 	InfoDlg( QWidget *parent );
  17. 	virtual ~InfoDlg();
  18.  
  19. public slots:
  20. 	void SetText(const QString&);
  21. 	void CloseDialogAfter(int msec);
  22.  
  23. protected:
  24.  
  25. private:
  26. 	Ui::infoDlg ui;
  27. };
  28.  
  29. #endif __INFODLG_H__
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and the .cpp

Qt Code: 
  1. #include "InfoDlg.h"
  2. #include <QTimer>
  3.  
  4. InfoDlg::InfoDlg( QWidget *parent )
  5. : QDialog(parent)
  6. {
  7. 	ui.setupUi(this);
  8. 	setWindowFlags( Qt::FramelessWindowHint | Qt::Dialog );
  9. 	setAttribute( Qt::WA_DeleteOnClose );
  10. 	setWindowOpacity(0.8);
  11. }
  12.  
  13. InfoDlg::~InfoDlg()
  14. {
  15. }
  16.  
  17. void InfoDlg::SetText(const QString& text)
  18. {
  19. 	ui.infoLabel->setText(text);
  20. }
  21.  
  22. // close the dialog after x msec
  23. void InfoDlg::CloseDialogAfter(int msec)
  24. {
  25. 	QTimer::singleShot( msec, this, SLOT(close() ) );
  26. }
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Here the ui file for those that would reproduce the dialog
Qt Code: 
  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <ui version="4.0">
  3.  <class>infoDlg</class>
  4.  <widget class="QDialog" name="infoDlg">
  5.   <property name="geometry">
  6.    <rect>
  7.     <x>0</x>
  8.     <y>0</y>
  9.     <width>382</width>
  10.     <height>92</height>
  11.    </rect>
  12.   </property>
  13.   <property name="windowTitle">
  14.    <string>Dialog</string>
  15.   </property>
  16.   <layout class="QVBoxLayout" name="verticalLayout">
  17.    <item>
  18.     <widget class="QLabel" name="infoLabel">
  19.      <property name="text">
  20.       <string/>
  21.      </property>
  22.      <property name="alignment">
  23.       <set>Qt::AlignCenter</set>
  24.      </property>
  25.     </widget>
  26.    </item>
  27.   </layout>
  28.  </widget>
  29.  <resources/>
  30.  <connections/>
  31. </ui>
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Here an example of usage of the dialog

Qt Code: 
  1. void WaveWidget::EncodingStart()
  2. {
  3. 	dlg = new InfoDlg(this);
  4. 	dlg->SetText("Encoding process started");
  5. 	dlg->show();
  6. }
  7.  
  8. void WaveWidget::EncodingEnd()
  9. {
  10. 	if( !m_WaveDisplay->m_ListaMarcatori.isEmpty() )
  11. 	{
  12. 		m_WaveDisplay->deteleMarkers();
  13. 	}
  14.  
  15. 	m_WaveDisplay->waveSelectionStarted = false;
  16.  
  17. 	dlg->SetText("Encoding process finished");	
  18. 	dlg->CloseDialogAfter( 2000 );
  19. }
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The EncodingStart() and EncodingEnd() are two slot of WaveWidget connected to a separated thread so:

Qt Code: 
  1. void WaveWidget::CutSound()
  2. {
  3.    bool bg = false;
  4.    if( m_bgSndCheckBox->isChecked() )
  5. 	bg = true;
  6.  
  7.   WaveEncoder* encoderThread = new WaveEncoder( m_SoundName, m_outputDir, m_bgFile, bg, m_wave,   m_WaveDisplay );
  8.   connect( encoderThread, SIGNAL( started() ), this, SLOT( CodificaStart() ) );
  9.   connect( encoderThread, SIGNAL( finished() ), this, SLOT( CodificaEnd() ) );
  10.  
  11.   encoderThread->setOffset(m_soundOffset);
  12.   encoderThread->start();
  13. }
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I run the infoDlg in modeless mode with show() but unfortunately it block my gui ( gui doesn't accept further keyboard input and it's blocked ) I don't understand why.