command option in this scriptthe sbar set built-in method adjusts scroll bar proportionally in other wordsmoving one automatically moves the other it turns out that every scrollable object in tkinter--listboxentrytextand canvas--has built-in yview and xview methods to process incoming vertical and horizontal scroll callbacksas well as yscrollcommand and xscrollcommand options for specifying an associated scroll bar' callback handler to invoke all scroll bars have command optionto name an associated widget' handler to be called on moves internallytkinter passes information to all of these methodsand that information specifies their new position ( "go percent down from the top")but your scripts usually need never deal with that level of detail because the scroll bar and listbox have been cross-linked in their option settingsmoving the scroll bar automatically moves the listand moving the list automatically moves the scroll bar to move the scroll bareither drag the solid part or click on its arrows or empty areas to move the listclick on the list and either use your arrow keys or move the mouse pointer above or below the listbox without releasing the mouse button in all casesthe list and scroll bar move in unison figure - shows the scene after expanding the window and moving down few entries in the listone way or another figure - scrolledlist in the middle packing scroll bars finallyremember that widgets packed last are always clipped first when window is shrunk because of thatit' important to pack scroll bars in display as soon as possible so that they are the last to go when the window becomes too small for everything you can generally make do with less than complete listbox textbut the scroll bar is crucial tkinter tourpart