Combining selections

After drawing a marquee you can combine it with another marquee drawn over it. This feature helps in creating selections that are a combination of common shapes. In this context it is imperative that you follow the correct clicking order, since it makes a big difference which key is pressed first.

ALT (Macintosh: Option)
Press and hold the key before clicking and drawing. The crosshair cursor shows a small minus sign next to it.
This cursor indicates that the area drawn that overlaps the already selected area will be removed from the selection. This process can be repeated to create odd shaped selections.

SHIFT
Press and hold the key before and while drawing the second marquee. The crosshair cursor will show a small plus sign next to it.
This is the indication that the area drawn will be added to the already selected area. Please note that the areas do not have to be overlapping and you can create non-adjacent selections.

SHIFT+ALT (Macintosh: SHIFT+Option)
Press and hold the keys in the order SHIFT and then the second key before clicking and drawing. A small 'x' indicates that the final selection will be the area which is common to both marquees.