Apply solution for processwire/processwire-issues#252 - publish via page tree was showing "pub" button even when page was missing requirements. Note that this solution takes effect only upon page save in the page editor, so will not affect pages in an existing installation that may not be meeting requirements.

wire/core/Page.php

@@ -184,6 +184,13 @@ class Page extends WireData implements \Countable, WireMatchable {
 	 */
 	const statusOn = 1;
 
+	/**
+	 * Reserved status
+	 * #pw-internal
+	 * 
+	 */
+	const statusReserved = 2;
+
 	/**
 	 * Indicates page is locked for changes (name: "locked")
 	 * 
@@ -206,6 +213,7 @@ class Page extends WireData implements \Countable, WireMatchable {
 
 	/**
 	 * Page has a globally unique name and no other pages may have the same name
+	 * #pw-internal
 	 * 
 	 */
 	const statusUnique = 32;
@@ -224,8 +232,16 @@ class Page extends WireData implements \Countable, WireMatchable {
 	 */
 	const statusVersions = 128;
 
+	/**
+	 * Page might have incomplete data because there were errors when last saved interactively or may be missing required fields
+	 * #pw-internal
+	 * 
+	 */
+	const statusIncomplete = 256;
+
 	/**
 	 * Page is temporary. 1+ day old unpublished pages with this status may be automatically deleted (name: "temp"). 
+	 * Applies only if this status is combined with statusUnpublished. 
 	 * #pw-internal
 	 * 
 	 */
@@ -287,11 +303,14 @@ class Page extends WireData implements \Countable, WireMatchable {
 	 * 
 	 */
 	static protected $statuses = array(
+		'reserved' => self::statusReserved,
 		'locked' => self::statusLocked,
 		'systemID' => self::statusSystemID,
 		'system' => self::statusSystem,
+		'unique' => self::statusUnique,
 		'draft' => self::statusDraft,
 		'versions' => self::statusVersions,
+		'incomplete' => self::statusIncomplete, 
 		'temp' => self::statusTemp,
 		'hidden' => self::statusHidden,
 		'unpublished' => self::statusUnpublished,
@@ -3712,7 +3731,7 @@ class Page extends WireData implements \Countable, WireMatchable {
 	 *  - `integer|string|array`: Status number(s) or status name(s) to set the current page status (same as $page->status = $value)
 	 * @param int|null $status If you specified `true` for first argument, optionally specify status value you want to use (if not the current).
 	 * @return int|array|Page If setting status, `$this` is returned. If getting status: current status or array of status names is returned.
-	 * @see Page::addStauts(), Page::removeStatus(), Page::hasStatus()
+	 * @see Page::addStatus(), Page::removeStatus(), Page::hasStatus()
 	 * 
 	 */
 	public function status($value = false, $status = null) {