: _blen ( buf -- length of str in buf )
    DUP BEGIN C@+ 0x20 < UNTIL -^ 1- ;
: _rbufsz ( size of linebuf to the right of curpos )
    EDPOS @ 64 MOD 63 -^ ;
: i COMPILE I ; IMMEDIATE ( save overshadowed )
: _I ( I without _pln and _type. used in VE )
    _rbufsz IBUF _blen 2DUP > IF
        TUCK - ( ilen chars-to-move )
        SWAP EDPOS @ _cpos 2DUP + ( ctm ilen a a+ilen )
        3 PICK MOVE- ( ctm ilen ) NIP ( ilen )
    ELSE DROP 1+ ( ilen becomes rbuffsize+1 ) THEN
    DUP IBUF EDPOS @ _cpos ROT MOVE ( ilen ) EDPOS +! BLK!! ;
: I IBUF _type _I EDPOS @ 64 / _pln ;