How to find out the current widget size in tkinter?
somewidget.winfo_width() and somewidget.winfo_height() give 1. You need to update Tk (issue tk.update()) before getting these values.
Use somewidget.winfo_width() and somewidget.winfo_height() to get the actual widget size, the somewidget['width'] property is only a hint given to the geometry manager.