'Adjust scrollbars according to window- and canvas-size.'

def adjustScrolls(self):

    cwidth = self._canvas.winfo_width()
    cheight = self._canvas.winfo_height()
    self._canvas.xview_moveto(((0.5 * (self.canvwidth - cwidth)) / self.canvwidth))
    self._canvas.yview_moveto(((0.5 * (self.canvheight - cheight)) / self.canvheight))
    if ((cwidth < self.canvwidth) or (cheight < self.canvheight)):
        self.hscroll.grid(padx=1, in_=self, pady=1, row=1, column=0, rowspan=1, columnspan=1, sticky='news')
        self.vscroll.grid(padx=1, in_=self, pady=1, row=0, column=1, rowspan=1, columnspan=1, sticky='news')
    else:
        self.hscroll.grid_forget()
        self.vscroll.grid_forget()
