The Crop image transform toolbar operator crops the image down to the minimum enclosing rectangle of the target box in the Transform toolbar . Normally, this is the [Selection] or the name of some saved selection. Crop has no effect if no selection is present.
The example above selects Tokyo airport and then crops down to the size of the selection.
Crop works fine even if the selected pixels are in many different discontinuous regions.
Classic mouse cursor "box" crops may be easily achieved using select box mouse selection. If desired, the selection style can be set to border to show the selection as a box.