I recently acquired a Lenovo E550 and had the same problem, I solved it by using
xautomation) along with
Why the other answers won't work entirely?
@Ed Villegas (nor @Null Pointer) answer won't work because some of the keys located above the numeric part are not unique keys by themself (e.g. the lock key is related to the Super+L combination). When
xev is used to try to find the lock key keycode it returns both the Super and the L keycodes, you just have to interpret the
xev output line by line.
For @Bahax and @John Finegan: Shift+F10 is a context menu key, it doesn't work in all the applications and it doesn't provide the same functions as Menu. If you select a file in the file explorer and press Menu the context menu for the file itself should pop-up, this does not happen with the Shift+F10 combination, it would provide a context menu for the window instead.
@Danial Behzadi takes a similar approach to the people in the 2nd item, but linking the keyboard combination to one key through a keystroke simulator, it will link the key to the Shift+F10 and provide the same result.
The answer that works
It is important to take into account that the key that is not present in the ThinkPad keyboard is the Menu (that is it's name), it is shown in the following picture:
Although the key is not present, it's keycode should exist in your computer, you can find it by printing the keycode table with
xmodmap -pke | grep Menu which should give you something like:
With that in mind, install
xautomation (in order to use
xte for keystroke simulations) like in @Danial Behzadi answer:
sudo apt-get install xautomation
And create a custom shortcut, in the Trigger press the key that you want to be the shortcut, and in the
xte 'key Menu'. Apply and test.