Is the display manager only a login screen?

[Paul Smith]

On Thu, May 26, 2011 at 2:30 PM, Patrick O'Callaghan
<pocallaghan at gmail.com> wrote:
>> Is the display manager only a login screen? Or is it also the backbone
>> of the desktop manager?
>>
>> Could you please elaborate a bit on this? I have searched on Google
>> for it, and got the impression that a display manager is not more than
>> a login screen.
>
> A display manager manages displays (duh!), since you can have more than
> one and they might have different specs and be located in different
> places. A typical function is to fire up a login screen, which provides
> the entry point to a desktop manager (often selectable). However the
> display manager doesn't participate in this beyond detecting when the
> desktop manager terminates and putting up a new login screen.
>
> For more detail, you need to read up on the X Window System. This is not
> a specifically Linux thing. In fact it's not strictly even a Unix thing.

Thanks, Patrick, for your clarification. If a display manager provides
only a login screen, then what is the point of discussing whether a
display manager is lightweight or not, as the ongoing discussion on
the this list?

Paul