dijit/form/TextBox's module level summary is:
var TextBox = declare("dijit.form.TextBox", [_FormValueWidget, _TextBoxMixin], {
// summary:
// A base class for textbox form inputs
However, it's appearing in the API viewer (and presumably the details.xml) as the summary from a property of InlineEditBox whose value is TextBox:
// editor: String|Function
// MID (ex: "dijit/form/TextBox") or constructor for editor widget
editor: TextBox,