Tkinter/scrollbar/canvas question

[Saul Spatz]

It works if you change it like so:

from tkinter import *
class ShowList(Frame):
        def __init__(self, root):
                Frame.__init__(self, root)
                self.grid()
                self.draw_widgets()
        def draw_widgets(self):
                cframe = Frame(self)
                cframe.grid(row=1, sticky=N+S+E+W)
                canv = Canvas(cframe)
                canv.grid(row=0, column=0, sticky=N+S+E+W)
                vscroll = Scrollbar(cframe, orient=VERTICAL, command=canv.yview)
                hscroll = Scrollbar(cframe, orient=HORIZONTAL, command=canv.xview)
                vscroll.grid(row=0, column=1, sticky=N+S)
                hscroll.grid(row=1, column=0, sticky=E+W)
                canv["xscrollcommand"] = hscroll.set
                canv["yscrollcommand"] = vscroll.set
                aframe = Frame(canv)
                id = canv.create_window(0,0,window=aframe, anchor=N+W)
                for i in range(0,100):
                        Label(aframe, text=str(i), anchor=N+W).grid(row=i, column=0)
                aframe.update_idletasks()
                canv["scrollregion"]=canv.bbox(ALL)
root  = Tk()
m=ShowList(root)
root.mainloop()

You need to do the update_idletasks to force the canvas to be mapped before you figure out the bounding box.  Until the canvas is mapped to the screen, the bounding box is (0,0,1,1) so there no scrolling possible.  (You can call update_ideltasks through any widget.)

That said, I wonder why you're putting widgets in the frame instead of putting objects directly on the canvas.  The way you're doing it you can't use tags, which are what really give the canvas its power.

Saul