Alas, not everything works as you might hope! Sometimes there are problems in using a keyboard layout, and it is often hard to know what is happening.

The first question to ask is whether the program you are using supports Unicode. The vast majority of programs do support it. Some older programs do not, and some have limited support. Often the developer can tell you whether a program will work with Unicode. The usual symptoms are either that the keyboard layout simply doesn’t work, or the characters produced are not what you expect, or that some characters don’t appear while others do.

Mac OS X has had an annoying tendency, though it has been improving, of suddenly switching input sources without the user making the change. This might be when you switch applications, or even move between fields on a web form. The nastiest trick is when you tab into a password field in Safari, which may switch keyboard layouts to some standard such as US.

Apple seems to privilege the system’s keyboard layouts. You must have at least one active, so you cannot just have your own keyboard layouts active. If the input source switches by itself, it will often be to one of the system’s keyboard layouts. Just keep an eye on the input menu if something appears to be going wrong.

If you cannot find your keyboard layout in the International preference pane, there is a small possibility that there is an error in the XML format. The way to verify this is to look in the Console application to see if there is some message that mentions the string uchr, probably complaining about some error. If this is the case, please contact the developer at the email address in the Read Me file.

Another issue that people see is when they try to change some keys in unusual ways. In particular, there what are referred to as the “special” keys, that is, ones that do no produce a regular character, such as the arrow keys, delete, help, and so on. Trying to change the output of these keys, or making another key behave like one of them, is not always supported. Some of Apple’s own applications do not support this. You are best off not trying this, or being sure that the application you use will work correctly.