RE: Microsoft was right with explorer windows

["Wesley Felter" <wesf cs utexas edu>]

> Dan Kaminsky wrote:
> 
> > Think about it...if you have ten explorer apps, and one of them presses
> > exit, shouldn't convention dictate THEY ALL close, because explorer.exe
> > should be exiting?
> >
> > Close was the right choice.
> 
> No.  Close shouldn't even shut down the application, but with the 
> Explorer,
> it does.
> 
> I'm not sure I follow your logic.  Each instance of Explorer uses the same
> binary file.  However, each instance (i.e. process) executes in a separate
> process space (i.e. chunk of virtual memory).  This is a universal concept
> (ignoring the special case of 16-bit apps).
> 
> You are suggesting that hitting Exit in one should send a signal to all
> other instances, across process boundaries, causing them to 
> close, too?  In
> that case, you're getting into IPC, which is quite an extended feature.

The problem here seems to be the difference between single-launch applications and multiple-launch applications. There are two common cases here: For a single-launch app, there can be only one instance of that application per user and all windows are owned by the same process. Single-launch is the only method supported on MacOS. For a multiple-launch app, each window is owned by a separate process. Multiple-launch is the default on Unix. An in-between style where there are several processes which each own several windows is possible but even more confusing.

The problem as I see it is that the user can't tell the difference between these two styles. When a user chooses File->Exit for a single-launch app, all of its windows go away. For a multiple-launch app, there is a question: Should exiting quit all the instances of the app or just one? Explorer gets around this by not having an Exit item, so it is obvious to the user that when they choose Close, that action only affects that window.

Close only affects the window it is invoked upon, and Exit affects the whole application. But the effect of Exit can be ambiguous when the scope of "the whole application" isn't obvious to the user.

Wesley Felter - wesf@cs.utexas.edu - Hack the Planet