Are you annoyed that german keyboard layout makes using the standard command + z for Undo rather cumbersome? Here is a layout which switches the y and the z key, only when command is pressed. This makes using the Undo shortcut so much more ergonomic.
The keymap was created using Ukulele and is supplied as a bundle and as a keymap.
You can either drop the keymap files in ~\Library\Keyboard Layouts or use Ukulele to do the installation for you via the included organiser.
[TODO] Add reference to Ukulele installation doc.
No, this keyboard layout only switches y and z when the command key is pressed. If not, y and z behave according to the german keyboard layout.
No, using System Preferences is not an option. While System Preferences can remap menu options, it needs to know the exact name of the menu option. In case of Undo many applications will change the menu option title depending on the current context. E.g. Undo typing or Undo delete 4 items which makes it almost impossible to completely solve this.
While karabiner is awesome, I wanted a solution that would not require any third party applications.