From The Document Foundation Wiki
Here are some suggestions for choosing what to crop:
- Focus the readers’ attention on the part being discussed, especially when the full dialog has already been shown and the text is referring to one particular part of it.
- Remove blank space in dialogs that are of standard size but use only a small portion of the area for data or selections. In most cases, cutting off the bottom portion (with the standard OK, Cancel, and Next buttons) does not reduce readers’ comprehension, especially when the full dialog has already been shown.
- Make a wide dialog (such as the ▸ one) fit on a page by cropping off the portion that is not essential to the discussion, for example the navigation tree on the left. In some cases (such as the dialog for customizing a Table of Contents), the optional Preview section can be deselected.