class TCanvas: public TPad

 Canvas default constructor.

 Canvas default constructor

 Create an embedded canvas, i.e. a canvas that is in a TGCanvas widget
 which is placed in a TGFrame. This ctor is only called via the
 TRootEmbeddedCanvas class.

  If "name" starts with "gl" the canvas is ready to receive GL output.

  Create a new canvas with a predefined size form.
  If form < 0  the menubar is not shown.

  form = 1    700x500 at 10,10 (set by TStyle::SetCanvasDefH,W,X,Y)
  form = 2    500x500 at 20,20
  form = 3    500x500 at 30,30
  form = 4    500x500 at 40,40
  form = 5    500x500 at 50,50

  If "name" starts with "gl" the canvas is ready to receive GL output.

  Create a new canvas with a predefined size form.
  If form < 0  the menubar is not shown.

  form = 1    700x500 at 10,10 (set by TStyle::SetCanvasDefH,W,X,Y)
  form = 2    500x500 at 20,20
  form = 3    500x500 at 30,30
  form = 4    500x500 at 40,40
  form = 5    500x500 at 50,50

  Create a new canvas at a random position.

  ww is the canvas size in pixels along X
      (if ww < 0  the menubar is not shown)
  wh is the canvas size in pixels along Y

  If "name" starts with "gl" the canvas is ready to receive GL output.

  Create a new canvas at a random position.

  ww is the canvas size in pixels along X
      (if ww < 0  the menubar is not shown)
  wh is the canvas size in pixels along Y

  Create a new canvas.

  wtopx,wtopy are the pixel coordinates of the top left corner of
  the canvas (if wtopx < 0) the menubar is not shown)
  ww is the canvas size in pixels along X
  wh is the canvas size in pixels along Y

  If "name" starts with "gl" the canvas is ready to receive GL output.

  Create a new canvas.

  wtopx,wtopy are the pixel coordinates of the top left corner of
  the canvas (if wtopx < 0) the menubar is not shown)
  ww is the canvas size in pixels along X
  wh is the canvas size in pixels along Y

 Initialize the TCanvas members. Called by all constructors.

 Build a canvas. Called by all constructors.

 Canvas destructor

 Browse.

 Actual canvas destructor.

 Set current canvas & pad. Returns the new current pad,
 or 0 in case of failure.
 See TPad::cd() for an explanation of the parameter.

 Remove all primitives from the canvas.
 If option "D" is specified, direct subpads are cleared but not deleted.
 This option is not recursive, i.e. pads in direct subpads are deleted.

 Emit pad Cleared signal.

 Emit Closed signal.

 Close canvas.

  Delete window/pads data structure

 Copy the canvas pixmap of the pad to the canvas.

  Draw a canvas.
  If a canvas with the name is already on the screen, the canvas is repainted.
  This function is useful when a canvas object has been saved in a Root file.
  One can then do:
     Root > Tfile f("file.root");
     Root > canvas.Draw();

 Draw a clone of this canvas
 A new canvas is created that is a clone of this canvas

 Draw a clone of this canvas into the current pad
 In an interactive session, select the destination/current pad
 with the middle mouse button, then point to the canvas area to select
 the canvas context menu item DrawClonePad.
 Note that the original canvas may have subpads.

 Report name and title of primitive below the cursor.

    This function is called when the option "Event Status"
    in the canvas menu "Options" is selected.

 Get editor bar.

 Embedded a canvas into a TRootEmbeddedCanvas. This method is only called
 via TRootEmbeddedCanvas::AdoptCanvas.

 Generate kMouseEnter and kMouseLeave events depending on the previously
 selected object and the currently selected object. Does nothing if the
 selected object does not change.

 Execute action corresponding to one event.

  This member function must be implemented to realize the action
  corresponding to the mouse click on the object in the canvas

  Only handle mouse motion events in TCanvas, all other events are
  ignored for the time being

 Turn rubberband feedback mode on or off.

 Flush canvas buffers.

 Force a copy of current style for all objects in canvas.

 Returns current top x position of window on screen.

 Returns current top y position of window on screen.

 Handle Input Events.

  Handle input events, like button up/down in current canvas.

 Is folder ?

 List all pads.

 Static function to build a default canvas.

 Set option to move objects/pads in a canvas.

  if set = 1 (default) graphics objects are moved in opaque mode
         = 0 only the outline of objects is drawn when moving them
  The option opaque produces the best effect. It requires however a
  a reasonably fast workstation or response time.

 Paint canvas.

 Prepare for pick, call TPad::Pick() and when selected object
 is different from previous then emit Picked() signal.

 Emit Picked() signal.

 Emit Selected() signal.

 Emit ProcessedEvent() signal.

 Recompute canvas parameters following a X11 Resize.

 Set option to resize objects/pads in a canvas.

  if set = 1 (default) graphics objects are resized in opaque mode
         = 0 only the outline of objects is drawn when resizing them
  The option opaque produces the best effect. It requires however a
  a reasonably fast workstation or response time.

 Execute the list of TExecs in the current pad.

 Save primitives in this canvas in C++ macro file with GUI.

 Save primitives in this canvas as a C++ macro file.
 This function loops on all the canvas primitives and for each primitive
 calls the object SavePrimitive function.
 When outputing floating point numbers, the default precision is 7 digits.
 The precision can be changed (via system.rootrc) by changing the value
 of the environment variable "Canvas.SavePrecision"

 Toggle batch mode. However, if the canvas is created without a window
 then batch mode always stays set.

 Set Width and Height of canvas to ww and wh respectively
 If ww and/or wh are greater than the current canvas window
 a scroll bar is automatically generated.
 Use this function to zoom in a canvas and naviguate via
 the scroll bars.

 Set cursor.

 Set Double Buffer On/Off.

 Fix canvas aspect ratio to current value if fixed is true.

 If isfolder=kTRUE, the canvas can be browsed like a folder
 by default a canvas is not browsable.

 Set selected canvas.

 Set canvas title.

 Set the canvas scale in centimeters.

  This information is used by PostScript to set the page size.
  xsize  = size of the canvas in centimeters along X
  ysize  = size of the canvas in centimeters along Y
   if xsize and ysize are not equal to 0, then the scale factors will
   be computed to keep the ratio ysize/xsize independently of the canvas
   size (parts of the physical canvas will be unused).

   if xsize = 0 and ysize is not zero, then xsize will be computed
      to fit to the current canvas scale. If the canvas is resized,
      a new value for xsize will be recomputed. In this case the aspect
      ratio is not preserved.

   if both xsize = 0 and ysize = 0, then the scaling is automatic.
   the largest dimension will be allocated a size of 20 centimeters.

 Stream a class object.

 Toggle pad auto execution of list of TExecs.

 Toggle event statusbar.

 Toggle toolbar.

 Toggle editor.

 Toggle tooltip display.

 Static function returning "true" if transparency is supported.

 Update canvas pad buffers.

 Used by friend class TCanvasImp.

 Check whether this canvas is to be drawn in grayscale mode.

 Set whether this canvas should be painted in grayscale, and re-paint
 it if necessary.

 Probably, TPadPainter must be placed in a separate ROOT module -
 "padpainter" (the same as "histpainter"). But now, it's directly in a
 gpad dir, so, in case of default painter, no *.so should be loaded,
 no need in plugin managers.
 May change in future.

 Access and (probably) creation of pad painter.

assert on IsBatch() == false?