Python/Tkinter: Cascading menus anchored at the right instead of the left
I was able to fix the problem. I first only noticed the problem within my own application, while others seemed to work normally. After trying a few other applications it seemed the problem wasn't limited to my own. I guess the ones I tried first didn't have the problem, because they likely used a different widget toolkit. The problem is caused by Windows (8.1), which automagically switched some settings for tablets (I have a semi-tablet: Lenovo Thinkpad Yoga).
The problem was solved by running the following command (press windows key + R to run commands)
shell:::{80F3F1D5-FECA-45F3-BC32-752C152E456E}This will get you to the "Tablet PC Settings". In the "Other"-tab you have to make sure "Left-handed" is selected. This will change the appearance of the menus to normal.