XmSelectionBox
Motif's generic pick-from-a-list dialog, and the parent of both the file dialog and the XmCommand prompt.
It subclasses XmBulletinBoard and consists of a heading, an XmList, a text field showing the current choice, and OK, Apply, Cancel and Help buttons. Clicking an item copies it into the field, but users can type anything they like. With XmNmustMatch set, the typed value is checked against the list and a miss goes to XmNnoMatchCallback instead of OK. XmCreateSelectionDialog wraps it in an XmDialogShell, and XmCreatePromptDialog builds the same widget without the list, a bare question with a text field.
Two subclasses became better known than the parent. XmFileSelectionBox added a filter and a directory list. XmCommand turned the list into a history of previous commands with the text field as the prompt, for programs that wanted a command line inside a graphical window.