is a variable defined in `
C source code
Its value is
- Automatically becomes buffer-local when set.
- This variable may be risky if used as a file-local variable.
Function to call to compose characters automatically.
This function is called from the display routine with four arguments:
FROM, TO, WINDOW, and STRING.
If STRING is nil, the function must compose characters in the region
between FROM and TO in the current buffer.
Otherwise, STRING is a string, and FROM and TO are indices into the
string. In this case, the function must compose characters in the