old_echo_code = tv_kb_echo([echo_code.i2.r])
This function will enable or disable keyboard echo for a TV window.
Valid values of echo_code are KEY_ECHO_NONE, KEY_ECHO_ALL,
KEY_ECHO_NOTAB, KEY_ECHO_NOCTRL, and KEY_ECHO_NOKP. Only echo of
printing keys is affected. Cursor movement keys such as the arrow keys
are always enabled. Keyboard echo is enabled by INTYPE at
program initialization. When echo is disabled, the program may use
the TV_GET_KEY routine to find out about key presses. The value of the
keyboard echo code before modification is returned in old_echo_code.
This function requires the following include files: