Snapping to Pixels
Now for some real precision. To snap elements to pixels, choose View > Snapping > Snap to Pixels. Flash creates a grid whose squares measure 1 pixel by 1 pixel (see Figure 5). To see the grid, you must set the Stage's magnification to at least 400%.
Figure 5 With Flash's Snap to Pixels feature enabled, a 1-pixel grid becomes visible at magnifications of 400% or greater. You can use this mode for precise positioning of graphic elements.