man, I have no clue what you think your script is supposed to do. When I run it, it gives me a mainwindow with 2 black boxes in it, and nzb file gets populated into the entry box with a mouse click

..... upon looking at your code, I see you create 2 mainwindows, ..... this is definitely bad.....and can lead to undefined behavior, iirc..... you even leave an empty mainwindow artifact on the screen..... use a toplevel instead of a mainwindow for secondary windows....tk only likes 1 mainwindow

.... are you trying to put the return value from the get_file sub onto your canvas?....it looks like you just copy'n'pasted some code together and are asking why dosn't it work?..... i don't do homework anymore...i help you correct it.. :-)