Re: wmmail and session management

[Michael ROGERS <M Rogers cs ucl ac uk>]

>>  Yes I am aware of this.  I am currently working on just such a window
>>  manager, and it is a messy way of doing stuff - the window manager has to
>>  make a list of windows and their sizes as shutdown (so we have essentially
>>  two copies of the session) and then as the windows popup it has to try and
>>  match up the windows with its own list and position them accordingly.
>>  Fun.  Does E get this right?  WM doesn't.
>
>This is not messy, since only the window manager knows how to
>position/reparent windows the right way.

 The window manager can still position and reparent the windows, but there is
no reason the application should not request the window position it had at the
end of the previous session when it maps its windows.

>And the session information is not duplicated.  Applications save their 
>state, which does not entail window positions.

 I thought the idea of Gnome session management was that things like the
current line number of the file being edited would be saved, transparently to
the user, so that logging out and logging back in would not change the
appearance of the desktop in any way. Window geometry seems to me to be a
fundamental part of this concept, and since applications will be remembering
how many windows the user had open and which files were open in which windows,
it makes sense that they should also remember where those windows were
positioned. All the application has to do is set the *user-specified* window
size and position properties when it restarts, which all window managers 
should honour. User-specified properties can be used because windows saved in 
the session can be assumed to have been positioned where the user wanted them.

>The window manager saves the window positions or whatever information it 
>needs to place them where they were.

 This could be done, but it would require a reliably unique persistent window
identifier, so that a window could be identified on restart as one of the 
windows stored in the session. As far as I know no such identifier exists, so 
using the window manager to save window geometry is an imperfect solution. It 
is obviously the only option for non-session-aware applications, but where a
cleaner solution exists I think we should use it, even if it requires a 
trivial modification to existing Gnome applications.


 - Michael Rogers