Selector Tool - Skew Field
The Skew field on the Selector Tool Infobar is used to skew the selection. To skew the selection:
Type a skew angle and press RETURN.
Click the arrow buttons to skew the selection.
Positive values skew the selection above the transformation center to the right. Negative values skew the selection above the transformation center to the right. The skew takes place along a horizontal line through the transformation center. This usually means a horizontal line through the center of the selection unless you have moved the transformation center.