How does one disable completion when nothing but tabs or spaces is on the line?

[Linda A. Walsh]

If I have nothing but tabs or spaces on a line, how do I disable 
completion but have it return the char typed? (space or tab) -- and if 
bash is looking for a command, then execute any command.

I.e.
>  <space><space><space>ls "works"
>  <tab><tab><tab>ls "sorta works (tab's are dropped/ignored) -- would 
want them echo'd.

2) In a continuation line, if it is a quote, treat TAB's as literals if
they are the first thing on a line:

a="
<space><space><space><space>a"
echo "$a" gives me 'a' indented 4 spaces

Want:
a="
<tab>a"
echo "$a" to indent 1 tab (usually 8 spaces, but terminal dependent)


3) within a command (like if/while/for...).. i.e.

works:

if ((1)) ;then
<space>echo x
fi

doesn't work:
if ((1)); then
<tab>echo x
fi

------------------

NOTE: I tried binding a key like 'backquote' ("`") to the completion 
character,
but it seems rebinding in readline doesn't work consistently.  Is that a 
bug?


Thanks!