Floating and Nonfloating Selections with CS5 Marquee Tool
Use Photoshop Creative Suite 5 selection tools to make images look as though you haven’t retouched or edited them — to make your photo look real, not contrived. The Marquee tool is the main selection tool; by that, we mean that you use it most often for creating selections.
The Marquee tool includes the Rectangular Marquee (for creating rectangular selections), Elliptical Marquee (for creating round or elliptical selections), and Single Row Marquee or Single Column Marquee tools (for creating a selection of a single row or column of pixels). You can access these other Marquee tools by holding down the default Rectangle Marquee tool in the Tools panel.
When you’re using a selection tool, such as the Marquee tool, your selections are floating by default, which means that you can drag them to another location without affecting the underlying pixels. You know that your selection is floating by the little rectangle that appears on the cursor.
If you want to, however, you can move the underlying pixels. Using the selection tool of your choice, just hold down the Ctrl (Windows) or Command (Mac) key to temporarily access the Move tool; the cursor changes to a pointer with scissors, denoting that your selection is nonfloating. Now, when you drag, the pixel data comes with the selection.
Hold down Alt+Ctrl (Windows) or Option+Command (Mac) while using a selection tool and drag to clone (copy) pixels from one location to another. Add the Shift key, and the cloned copy is constrained to a straight, 45-degree, or 90-degree angle.