Consider the difference between the original "Text" tool, and the new "Label" tool. (Text is applied to the canvas, can be painted over, magic applied to it, etc., and it cannot be edited or repositioned later. Labels can be edited, removed, resized, recolored, etc., but "float above" the canvas -- you cannot paint on them, or apply magic effects to them.)
We're occasionally asked whether Tux Paint provides the ability to "move objects" after they've been placed. Aside from the standard response that we'd like to eventually add a set of cut/copy/paste tools, let's assume "objects" to mean only "Stamps" (ignore other blitted objects, such as shapes, lines, paintbrush painting, and magic).
We could provide a new tool which, similar to how "Label" is almost identical to "Text", would be almost identical to "Stamps." (Let's call it "Stickers", since that's not a bad analogy -- a real-world stamp is inked and pressed onto paper, and you cannot remove the shape later, a real-world sticker can arguably be removed later and re-applied somewhere else.) The stickers would "float above" the canvas, and could not be drawn over, stamped over, or edited with magic effects. However, they could later be repositioned, resized, re-colored/re-tinted, flipped/mirrored, rotated (if/when we support that with Stamps), or removed altogether.
The main concerns are: storage (as well as automatically providing a "finished, flatted" PNG for use outside of Tux Paint, like we do with images that contain Labels), UI for manipulating them (would be similar issues tackled with Labels), UI for removing them (with Labels, the [Backspace] key can be used to "blank out" the label, which I believe then removes it completely), and possibly UI for reordering them (for when they overlap X/Y, rearranging their order in the Z direction / stack of all stickers).
Obviously, this feature should be made available optionally, so that it can be disabled for younger users. Stamps should remain as-is. We'd consider this a kind of "advanced feature," like Labels.