Fixed position for non-application items

Some specific items in launcher should IMO have fixed position in launcher and should be not "stackable" -not sure about the right word :/ Also stackable should be exclusively only application launchers or items dragged into launcher by users, but not system items.

I am talking about Trash, Removable media and other volumes(like NTFS) and Applications button (all marked on picture)
Also these item should be divided from other application launchers by some nice, simple separator. Only monochrome icons are not enough to make them cleary distinguishable because when users start pinning items to launcher, things get messy fast...