Unfortunately, the first tab defines the sketch name, and various other behind the scenes information.

e.g. if you save a sketsh as "mySketch" then it goes into a directory called mySketch, and processing knows to look for mySketch.pde, and treat that as the "main" file. Also any exported/run code actually gets wrapped in a bit of code like: "class mySketch extends PApplet {" so the main tab name is important.

I understand that's how it works now; I'm proposing that it could be made better by reprogramming it to use the file/folder name along with a separate sketch/tab name to locate the compiled file on the hard drive.

I would say that the way the file naming and tab deleting currently works is not "normal" software behaviour.  As such, it is not what the average user would expect and it makes the software less user friendly.  Sometimes different is good but in this case I just think it adds confusion.

From my perspective personally, I would like a lot more flexibility with the use of tabs.  One of the reasons I choose Firefox over IE is that I can have many tabs open in one program window rather than may program windows (I know IE7 has this now too but it's not as nice).  I would like to be able to do the same when I'm programming my robot project. What if each tab was treated and compiled as a separate program.  If you wanted a group of tabs to compile together, an option could be added to 'link' them together.  Otherwise, only the current selected tab would compile.  That would allow for easy switching between sketches while working on separate programs.  Or have many versions of your project stored in the same file etc.  It would also allow you to keep everything related to one entire project neatly in a single folder on the hard drive.

I did notice that the pop-up warning is different when deleting the first tab (unfortunately after the fact).  However, this brings us to a discussion of nomenclature.  I was under the impression that, in Processing lingo, the whole file is called the "sketchbook" and the individual tabs within the file were called "sketches."  Therefore, deleting a sketch, and deleting a tab would the same thing.  The warning messages, at best, are far to similar to one another for the first time user to notice at a glance.  At the very least, a big red exclamation mark with a warning that you are about to delete the entire file would be a great addition when you go to delete the leftmost tab.

Finally, I would like to make it clear that I am not trying to be negative.  I am only trying to help out, in the only way I can, to make a great tool even better.

Cheers

maybe it would simplify things, if the sketch deleting functionality would be removed. In my opinion it confuses more than it is useful.