I’d walk around and tell people to find more useful projects than wasting their time with adding tabs to each single GNOME application. Maybe the semmingly true rumors that one or another GNOME fellow might be somewhat lunatic (panties, anybody?) inspired theprogrammers who are implementing this.
One initial aspect: Calumn is totally right that tab implementations at application level are an effect of the lack of platform MDI support. We implement it at application level where we need solutions today and tomorrow, rather than the day after tomorrow. However, it is not yet clear whether tabs are useful at all for 90% of the applications.
Why tabs for Nautilus (and web browsers, spreadsheet, …) are a good idea
Let me briefly explain why I added tab support to Nautilus: It helps people with their workflow. Today, I used it to tidy up my document folders. I could use it to navigate between file operation source and destination folders extremely quickly, using the keyboard and ctrl-x, ctrl-v, and ctrl-page-up/down. I was two times as fast as with a console (where you need auto-completion), and five times as fast as with a mouse
Tab support for browser-like file managers is a good idea, because people know how to use the tab concept properly since it has been invented for web browser. It is also useful for spreadsheets, where you often compare multiple documents and calculations. It is also useful for having multiple conversations at once, because each of them is linear, and you can use the tabs to switch between losely-associated linear tasks or documents.
Why tabs for media players are a bad idea
On the other hand, tab support in Totem is ridiculous. Somebody must have put LSD into the GUADEC social event food, and everybody now feels like Syd Barrett and his Lucifer Cat!
Regarding Totem: It is already perfectly doing what it should do: Play a song or video, and let me queue more of them. One song or video at once. How can I watch two videos at once?
Why you should think first, and implement features afterwards (i.e. gcalctool tabs)!
Let me exemplify this regarding gcalctool:
Even my non-programmable pocket calculator (Casio FX-991ES) has more features than this non-noticeable desktop calculator. Amongst others, it can not deal with symbolic calculations, complex numbers, nature constants, variables. It does not even have a calculation history as I mentioned in a comment in Scott James’ blog. This is a shame! Before you implement such a craptastic feature, think about how it will be used! Again: gcalctool does not have any calculation history. This is as if I implemented tabs in Nautilus without implementing the back/forward button before, so you had to switch to a new tab each time you want to display a new folder.
Now I’ll do something useful and learn for my function theory exam.
You talented developers at GUADEC should also do something useful and fix the GTK+ tree view mouse interaction.
It turns out that the tab implementations were just mockups. Have fun at GUADEC!