completion-styles and moving the minibuffer point

[Philip Kaludercic]

My completion-styles set to

  '(basic initials partial-completion substring)

which is close to perfect for me.

I find it hard to verbalize an annoyance in understanding when
what completion-styles move the point around in the minibuffer. Maybe an
example might help: When selecting a buffer with C-x b, I might have two
buffers open "*Help*" and "*Bug Help*". Typing "Help<tab>" adds a "*",
but another <tab> does nothing. I have to manually C-a to the beginning
of the input and <tab> again for something to happen.

Sometimes Emacs moves the cursor automatically to wherever the possible
input diverges. I haven't understood when or why this happens, but I'd
like to have this happen more often. Does anyone know how?

-- 
        Philip Kaludercic