Most Windows open with three standard dialog buttons:

Cancel - Cancels dialog. Layout reverts back to its previous state. Cancel may be absent if reverting the action is not applicable. If the action affected objects on the layout, they can by reverted with the Undo command.
Help - Invokes on-line help for current command or dialog.
OK - Completes the dialog action. Layout is updated with current changes.
Entering Values
Map Window