Here is an easy solution that reduces confusion:
1- fix bug #563456 (associate .pptv files with pitivi)
2- remove the "New" toolbar button
3- remove the "Open" toolbar button, and put the "Import" button at its place
4- remove the "Save as" toolbar button (bug #558823)
5- reorder the remaining buttons to match the attached screenshot

Created attachment 127636 [details]
mockup

This is how it should look if you don't want to induce any confusion. I can assure you nobody will miss the "new", "save as" and "open" toolbar buttons.

Created attachment 127638 [details] [review]
Patch that cleans up the toolbar

Apply or die trying.

I have problems with this, and I'm writing the UI...

In trunk I have fixed the filtering on the open dialog so that it filters out files that don't end with recognized extensions (currently only .pptv). I tend to agree with you on the toolbar layout, but I think we should leave the final say.

OK for the toolbar-cleanup patch

*** Bug 574563 has been marked as a duplicate of this bug. ***

i like the idea

*** Bug 590356 has been marked as a duplicate of this bug. ***

Created attachment 146921 [details] [review]
Cleans up the toolbar

For your convenience, I've updated the patch so it can be applied with "git am" directly

Attachment 146921 [details] pushed as d19cfba - Cleans up the toolbar