In former times, Windows programs such as Word or Excel or Quattro Pro all had two windows: an outer application window and an inner document window. (We Mac users thought it was cumbersome and silly). Closing the last document window still left the application running, and the screen would be taken up by the blank application window until you either closed the app (by closing its window or otherwise) or opened a new document. You could also Alt-tab to some other application and leave Excel running.
Nowadays, many Windows programs (including MS Office apps) no longer have the application window.
That apparently means that when you close the last document window (like, say, a letter written in Microsoft Word), Word itself exits. (On the Mac, most applications remain running even when the last document window is closed; it leaves nothing behind except its menu set until you open another document).
I assume it is inefficient to exit out of an application program if you’re going to want it launched again immediately to open a different document. Is modern Windows actually doing that when you close the last document window? I can’t tell for sure – if I double-click a .docx document on the desktop or in my documents folder, I get the Word splash screen as if the application were launching even when other documents remain open already. But on the task bar at the bottom there’s no longer an underbar after the last document window closes.
Is the spread of SSD drives making all of this somewhat irrelevant and Microsoft wrote its OS in anticipation of not having to care one way or the other or something?
I just did some testing (Word and Excel 2016). You can add the “Close File” command to your Quick Access Toolbar and then use that to close the last document without the application itself closing.
As you say Microsoft went through a stage of using MDI in Office and other apps and then abandoned it.
As I recall the “vision” of the time is that different types of document would gradually merge into one so that instead of having “a spread sheet”, “a presentation” etc you would just have a document into which you put content of, potentially, different types. The MDI interface (at least as it was applied in Office) was meant to support that ideal by, eventually, just having one window in which all sorts of document types would be manipulated.
If that last sentence doesn’t sound entirely convincing I wasn’t entirely convinced myself at the time. It’s possible my lack of conviction is due to my having misunderstood their aims or simply that there was a significant amount of BS involved in the first place.
I don’t believe that the adoption of MDI was driven by performance factors. For what it’s worth my recollection is that there was some jaw droppingly slow aspects of the whole “embed your spread sheet inside a Word document” endeavour to the degree to which it was implemented.
windows doesn’t immediately evict program code from system memory when you close it. if you immediately re-launch it, much of what it loaded into memory when you first started it is still there and will load faster on a re-launch.
also, if it’s a program you use a lot, Windows will even pre-load it at boot time (via SuperFetch) so it doesn’t take as long for the program to load.
My Excel is kinda buggered right now, in Word I opened two documents and the behaviour was exactly as you described - closing the last document with the X would also close Word.
As Manson1972 said, there are ways around that. I use ctrl-F4 to close the document window, leaving Word running.
The splash screen just means that there’s a new instance of an entity that contains a Word document. Once you’ve opened the first one the necessary framework code hangs around until the memory it’s using is needed for something else. If you use Word or Excel or whatever a lot, then Windows will load much of the necessary code as part of the boot-to-desktop process.