class TQtWidget: public QWidget

 Adjust the widget buffer size

 Alias for GetCanvas method

 static: return TCanvas by TQtWidget pointer

 static: return the TQtWidget backend for TCanvas *canvas object

 static: return TQtWidget by TCanvas id

 Instantiate ROOT from within Qt application if needed
 Return the TRint pointer
 Most parametrs are passed to TRint class ctor

 Bool_t prompt = kTRUE;  Instantiate ROOT with ROOT command prompt
                 kFALSE; No ROOT prompt. The default for Qt GUI applications

  The prompt option can be defined via ROOT parameter file ".rootrc"
 .rootrc:
    . . .
  Gui.Prompt   yes

 Erases the entire widget and its double buffer

 [slot] to make this embedded canvas the current one

 [slot] to make this embedded canvas / pad the current one

 [slot] Disconnect the Qt widget from TCanvas object before deleting
 to avoid the dead lock
 one has to set CanvasID = 0 to disconnect things properly.

 [slot]  to allow Qt signal refreshing the ROOT TCanvas if needed
 use the permanent single shot timer to eliminate
 the redundand refreshing for the sake of the performance

 [slot]  to allow Qt signal refreshing the ROOT TCanvas if needed

  remember my host TCanvas and adopt its name

 The custom response to the special WIN32 events
 These events are not present with X11 systems

 The custom response to the Qt QContextMenuEvent
 Map QContextMenuEvent to the ROOT kButton3Down = 3  event

 The custom response to the Qt QFocusEvent "in"
 this imposes an extra protection to avoid TObject interaction with
 mouse event accidently

 The custom response to the Qt QFocusEvent "out"
 this imposes an extra protection to avoid TObject interaction with
 mouse event accidently

 Map the Qt mouse press button event to the ROOT TCanvas events
 Mouse events occur when a mouse button is pressed or released inside
 a widget or when the mouse cursor is moved.

  Map the Qt mouse move pointer event to the ROOT TCanvas events
  kMouseMotion   = 51,
  kButton1Motion = 21, kButton2Motion = 22, kButton3Motion = 23, kKeyPress = 24

  Map the Qt mouse button release event to the ROOT TCanvas events
   kButton1Up     = 11, kButton2Up     = 12, kButton3Up     = 13

  Map the Qt mouse double click button event to the ROOT TCanvas events
  kButton1Double = 61, kButton2Double = 62, kButton3Double = 63

 Map the Qt key press event to the ROOT TCanvas events
 kKeyDown  =  4

 Map the Qt key release event to the ROOT TCanvas events
 kKeyUp    = 14

 Map the Qt mouse enters widget event to the ROOT TCanvas events
 kMouseEnter    = 52

  Map the Qt mouse leaves widget event to the ROOT TCanvas events
 kMouseLeave    = 53

 The widget will be erased and receive a paint event immediately after
 processing the resize event.
 No drawing need be (or should be) done inside this handler.

 Set the default save format for the widget

  TQtWidget::Save(const QString &fileName) is a public Qt slot.
  it saves the double buffer of this object using the default save
  format  defined the file extension
  If the "fileName" has no extension the "default" format is to be used instead
  The default format is "PNG".
  It can be changed with the TQtWidget::SetSaveFormat method

  TQtWidget::Save(const QString &fileName) is a public Qt slot.
  it saves the double buffer of this object using the default save
  format  defined the file extension
  If the "fileName" has no extension the "default" format is to be used instead
  The default format is "PNG".
  It can be changed with the TQtWidget::SetSaveFormat method

  TQtWidget::save is a public Qt slot.
  it saves the double buffer of this object using QPixmap facility

 Set the double buffered mode on/off

 Stretch the widget during sizing

 Response to the "exit size event"

  Set new fPaint flag
  Returns: the previous version of the flag

 Custom handler of the Qt show event
 Non-spontaneous show events are sent to widgets immediately before
 they are shown.
 The spontaneous show events of top-level widgets are delivered afterwards.

 Custom handler of the Qt paint event
 A paint event is a request to repaint all or part of the widget.
 It can happen as a result of repaint() or update(), or because the widget
 was obscured and has now been uncovered, or for many other reasons.

  sets the preferred size of the widget.

  returns the preferred size of the widget.

 returns the smallest size the widget can have.

  returns a QSizePolicy; a value describing the space requirements

 Set or unset the user status bits as specified in f.

 Create (if needed) and return the buffer

  return the current widget buffer;

  Proxy methods to access the TCanvas selected TObject
  and last processed event

----- bit manipulation

----- Private bits, clients can only test but not change them

 emit the Qt signal when the double buffer of the TCamvas has been filled up