When you use the Move tool, you can do more than just drag a layer around the document on which you’re working. You can also drag a layer from one image window to another. This copies the selected layers into the second document. The copied layers will be positioned directly above the layer that was active in the second document. This is similar to copying and pasting, but it takes up a lot less memory because Adobe Photoshop CS2 doesn’t store the image on the clipboard. You can achieve the same result by dragging the name of a layer from the Layers palette onto another document window, regardless of which tool is active.
Note: When dragging between documents, Adobe Photoshop CS2 will position the layer based on where your cursor was when you clicked the image and where you released the mouse button in the second document. Holding Shift when dragging between documents will cause the layers to end up in the center of the destination document (if no selection is active), or centered on any active selection.
If the image you’re dragging to another document is considerably larger than the destination document, you’ll need to choose Edit>Transform>Scale to resize the image until it is an appropriate size for the destination document. If you can’t see the transformation handles, just type Command-0 (zero) to zoom out until the handles become visible.
When you drag layers between documents, occasionally an image will appear as if it has not only been copied, but also scaled at the same time. That’s not what’s really happening. Instead, you’re viewing the two images at different magnifications. Look at the tops of the documents; if the percentages do not match, the image size will appear to change when you drag the image between the documents. If you view both images with the same magnification, this won’t happen. It doesn’t change how large the image is; it simply gives you a preview of how large it will look. It’s just like putting your hand under a magnifying glass: Your hand looks larger, but when you pull your hand out, it looks normal again.