class HHistoVisual: public TGMainFrame

 Constructor of the class HHistoVisual.

 Destructor of the class HHistoVisual.

 This function closes the window.

 This function processes all GUI widgets.

 This function changes the button color to default one (gray).

 This function changes the button color to green.

 This function draws an object of the class HHistogram.

 This function sets the fields with the values of drawing settings.
 mode = 1 -- sys default
 mode = 2 -- hist default

 This function calculates the xDiv and yDiv parameters which are used
 to divide the canvas into subpads.
 This function is used in case of the automatic display layout
 (checkbutton "Multiple selection" is engaged).
 The function takes as an input parameter the total number of histogrammes
 to be displayed.
 Called from automaticDraw()

 This function draws a set of histogrammes in the canvas in case of
 the automatic display layout (checkbutton "Multiple selection" is engaged).
 Called when the button "Draw" is clicked.

 This function draws a histogram in the canvas in case of
 the user defined display layout
 (checkbutton "Multiple selection" is in the up position).
 Called when the button "Draw" is clicked.

 This function clears all text fields.

 This function checks if the display layout is set.

 This function highlights the entry in the combo box.

 This function returns the text in the highlighted entry of the combo box.

 This function updates the list of histogrammes.

 This function calculates dimensions (x1,y1,x2,y2) of the pad for
 the histogram with idx = index.

 This function redraws the layout buttons.

 This function creates the display canvas if necessary.

 This function saves to a buffer the current drawing options.

 This function fills all the drawing options fields with the buffer content.