Available options:
Angle
Determines the angle of the shearing in degree.
Preview
Switches on/off the preview on the right part of the window.
Use current color
As a shearing by its very nature adds additional size to an image, the new areas have to be filled with a color. If this option is active the current color is used as filling color, black otherwise.
Switch direction
Switches the direction in which the image is sheared.
Perform
This performs the operation. Before calculation starts the image is fixed and all undo-steps are deleted.