Hacking Selection Mask - Part 3

Knowing how to repositioning precisely an active selection mask by selecting a lasso tool or marquee. Just place the tool pointer in the selection, and then move and drag the selection to a new position. If you know the coordinates of where you want to reposition it, choose Select➜Transform Selection, or select the command from the contextual menu and then enter the coordinates in the options bar to positioning it precisely. Alternately, you can also use the arrow keys to nudge the selection, regardless of whether it’s being transformed.

To have any modification on your selections, just go to menu Select➜Modify; then, from the submenu, choose Border, Smooth, Expand or Contract that allows you to enter any value in pixels in the pop-up dialog box.

Adding, Subtracting and Intersecting Selections. You can add to, subtract from, or intersect with a selection while creating it or after the event.To do so, press Shift to add;Alt (Windows),Opt (Mac OS) to subtract; Alt+Shift (Windows), Opt+Shift(Mac OS) to intersect. You can also specify an option for the selection tool in the options bar before you use it by clicking one of the buttons. The options are, from left to right, New Selection, Add to Selection, Subtract from Selection and Intersect with Selection.