diff --git a/ChangeLog b/ChangeLog
index 64ce7979..39fa1096 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,15 @@
    Make doc_at() debug function check idx is within range.
  * src/build.c, src/search.c:
    Minor formatting.
+ * src/build.c, src/prefs.c, src/plugindata.h, src/callbacks.c,
+   src/search.c, src/document.c, src/document.h, src/ui_utils.c:
+   Bring back GeanyDocument::is_valid field as it is clearer and more
+   descriptive than using doc->index != -1.
+   Add deprecated macros DOC_IDX_VALID and DOC_IDX in plugindata.h,
+   which can make porting outside plugins easier; of course, it is
+   better to rewrite the code to use document pointers.
+   Use is_valid instead of the DOC_VALID macro when iterating over
+   documents_array, as there are never NULL pointers in it.
 
 
 2008-06-16  Enrico Tröger  <enrico(dot)troeger(at)uvena(dot)de>
diff --git a/src/build.c b/src/build.c
index b5ac2103..9cf27cd7 100644
--- a/src/build.c
+++ b/src/build.c
@@ -390,7 +390,7 @@ static void clear_errors(GeanyDocument *doc)
 
 			for (i = 0; i < documents_array->len; i++)
 			{
-				if (DOC_VALID(documents[i]))
+				if (documents[i]->is_valid)
 					editor_clear_indicators(documents[i]);
 			}
 			break;
diff --git a/src/callbacks.c b/src/callbacks.c
index 56cd4150..63a1e1ef 100644
--- a/src/callbacks.c
+++ b/src/callbacks.c
@@ -97,7 +97,7 @@ static gboolean check_no_unsaved(void)
 
 	for (i = 0; i < documents_array->len; i++)
 	{
-		if (DOC_VALID(documents[i]) && documents[i]->changed)
+		if (documents[i]->is_valid && documents[i]->changed)
 		{
 			return FALSE;
 		}
diff --git a/src/document.c b/src/document.c
index be4fa229..d1713d46 100644
--- a/src/document.c
+++ b/src/document.c
@@ -127,7 +127,7 @@ GeanyDocument* document_find_by_real_path(const gchar *realname)
 	{
 		GeanyDocument *doc = documents[i];
 
-		if (documents[i]->index == -1 || ! doc->real_path) continue;
+		if (! documents[i]->is_valid || ! doc->real_path) continue;
 
 		if (filenamecmp(realname, doc->real_path) == 0)
 		{
@@ -175,7 +175,7 @@ GeanyDocument *document_find_by_filename(const gchar *utf8_filename)
 	{
 		doc = documents[i];
 
-		if (documents[i]->index == -1 || doc->file_name == NULL) continue;
+		if (! documents[i]->is_valid || doc->file_name == NULL) continue;
 
 		if (filenamecmp(utf8_filename, doc->file_name) == 0)
 		{
@@ -200,7 +200,7 @@ GeanyDocument *document_find_by_sci(ScintillaObject *sci)
 
 	for (i = 0; i < documents_array->len; i++)
 	{
-		if (documents[i]->index != -1 && documents[i]->sci == sci)
+		if (documents[i]->is_valid && documents[i]->sci == sci)
 			return documents[i];
 	}
 	return NULL;
@@ -327,15 +327,15 @@ void document_apply_update_prefs(GeanyDocument *doc)
 }
 
 
-/* Sets index to -1 and initializes some members to NULL, to mark it uninitialized.
- * The document index is set in document_create() to mark it as valid. */
+/* Sets is_valid to FALSE and initializes some members to NULL, to mark it uninitialized.
+ * The flag is_valid is set to TRUE in document_create(). */
 static void init_doc_struct(GeanyDocument *new_doc)
 {
 	Document *full_doc = DOCUMENT(new_doc);
 
 	memset(full_doc, 0, sizeof(Document));
 
-	new_doc->index = -1;
+	new_doc->is_valid = FALSE;
 	new_doc->has_tags = FALSE;
 	new_doc->auto_indent = (editor_prefs.indent_mode != INDENT_NONE);
 	new_doc->line_wrapping = editor_prefs.line_wrapping;
@@ -477,6 +477,7 @@ static GeanyDocument *document_create(const gchar *utf8_filename)
 	}
 	this = documents[new_idx];
 	init_doc_struct(this);	/* initialize default document settings */
+	this->index = new_idx;
 
 	this->file_name = g_strdup(utf8_filename);
 
@@ -504,7 +505,7 @@ static GeanyDocument *document_create(const gchar *utf8_filename)
 
 	ui_document_buttons_update();
 
-	this->index = new_idx; /* do this last to prevent UI updating with NULL items. */
+	this->is_valid = TRUE;	/* do this last to prevent UI updating with NULL items. */
 	return this;
 }
 
@@ -543,7 +544,7 @@ gboolean document_remove_page(guint page_num)
 		g_free(doc->real_path);
 		tm_workspace_remove_object(doc->tm_file, TRUE, TRUE);
 
-		doc->index = -1;
+		doc->is_valid = FALSE;
 		doc->sci = NULL;
 		doc->file_name = NULL;
 		doc->real_path = NULL;
@@ -2487,7 +2488,7 @@ void document_delay_colourise()
 	doc_indexes = g_array_new(FALSE, FALSE, sizeof(gint));
 	for (n = 0; n < (gint) documents_array->len; n++)
 	{
-		if (DOC_VALID(documents[n]))
+		if (documents[n]->is_valid)
 			g_array_append_val(doc_indexes, n);
 	}
 	delay_colourise = TRUE;
@@ -2527,7 +2528,7 @@ void document_colourise_new()
 	/* colourise all in the doc_set */
 	for (n = 0; n < documents_array->len; n++)
 	{
-		if (doc_set[n] && documents[n]->index != -1)
+		if (doc_set[n] && documents[n]->is_valid)
 			sci_colourise(documents[n]->sci, 0, -1);
 	}
 	delay_colourise = FALSE;
@@ -2589,7 +2590,7 @@ gboolean document_account_for_unsaved(void)
 	/* all documents should now be accounted for, so ignore any changes */
 	for (i = 0; i < len; i++)
 	{
-		if (documents[i]->index != -1 && documents[i]->changed)
+		if (documents[i]->is_valid && documents[i]->changed)
 		{
 			documents[i]->changed = FALSE;
 		}
@@ -2605,7 +2606,7 @@ static void force_close_all(void)
 	/* check all documents have been accounted for */
 	for (i = 0; i < len; i++)
 	{
-		if (documents[i]->index != -1)
+		if (documents[i]->is_valid)
 		{
 			g_return_if_fail(!documents[i]->changed);
 		}
diff --git a/src/document.h b/src/document.h
index 476fc344..677b35b9 100644
--- a/src/document.h
+++ b/src/document.h
@@ -69,6 +69,8 @@ extern GeanyFilePrefs file_prefs;
  **/
 struct GeanyDocument
 {
+	/** General flag to represent this document is active and all properties are set correctly. */
+	gboolean		 is_valid;
 	gint			 index;		/**< Index in the documents array. */
 	/** Whether this %document support source code symbols(tags) to show in the sidebar. */
 	gboolean		 has_tags;
@@ -131,15 +133,9 @@ extern GPtrArray *documents_array;
  * This is useful when @a doc_ptr was stored some time earlier and documents may have been
  * closed since then.
  * @note This should not be used to check the result of the main API functions,
- * these only need a NULL-pointer check - @c p_document->get_current() != @c NULL.
- * This is only useful when iterating over the documents array or when using stored document
- * pointers like in msgwindow treeviews. */
+ * these only need a NULL-pointer check - @c p_document->get_current() != @c NULL. */
 #define DOC_VALID(doc_ptr) \
-	((doc_ptr) != NULL && (doc_ptr)->index != -1)
-
-/** NULL-safe way to get the index of @a doc_ptr in the documents array. */
-#define DOC_IDX(doc_ptr) \
-	(doc_ptr ? doc_ptr->index : -1)
+	((doc_ptr) != NULL && (doc_ptr)->is_valid)
 
 /**
  *  DOC_FILENAME returns the filename of the %document corresponding to the passed index or
diff --git a/src/plugindata.h b/src/plugindata.h
index d57f10ee..bd5eeee7 100644
--- a/src/plugindata.h
+++ b/src/plugindata.h
@@ -36,12 +36,12 @@
 
 /* The API version should be incremented whenever any plugin data types below are
  * modified or appended to. */
-static const gint api_version = 69;
+static const gint api_version = 70;
 
 /* The ABI version should be incremented whenever existing fields in the plugin
  * data types below have to be changed or reordered. It should stay the same if fields
  * are only appended, as this doesn't affect existing fields. */
-static const gint abi_version = 38;
+static const gint abi_version = 39;
 
 /** Check the plugin can be loaded by Geany.
  * This performs runtime checks that try to ensure:
@@ -460,6 +460,12 @@ typedef PluginCallback GeanyCallback;
 
 #define doc_array documents_array
 
+/** NULL-safe way to get the index of @a doc_ptr in the documents array. */
+#define DOC_IDX(doc_ptr) \
+	(doc_ptr ? doc_ptr->index : -1)
+#define DOC_IDX_VALID(doc_idx) \
+	((doc_idx) >= 0 && (guint)(doc_idx) < documents_array->len && documents[doc_idx]->is_valid)
+
 #endif	/* GEANY_DISABLE_DEPRECATED */
 
 #endif
diff --git a/src/prefs.c b/src/prefs.c
index 7d13b59a..8fce8837 100644
--- a/src/prefs.c
+++ b/src/prefs.c
@@ -824,7 +824,7 @@ on_prefs_button_clicked(GtkDialog *dialog, gint response, gpointer user_data)
 				editor_prefs.use_tabs = use_tabs;
 				for (i = 0; i < documents_array->len; i++)
 				{
-					if (DOC_VALID(documents[i]))
+					if (documents[i]->is_valid)
 						editor_set_use_tabs(documents[i], editor_prefs.use_tabs);
 				}
 			}
@@ -977,7 +977,7 @@ on_prefs_button_clicked(GtkDialog *dialog, gint response, gpointer user_data)
 		/* re-colourise all open documents, if tab width or long line settings have changed */
 		for (i = 0; i < documents_array->len; i++)
 		{
-			if (DOC_VALID(documents[i]))
+			if (documents[i]->is_valid)
 			{
 				document_apply_update_prefs(documents[i]);
 				if (! editor_prefs.folding)
@@ -1046,7 +1046,7 @@ void on_prefs_font_choosed(GtkFontButton *widget, gpointer user_data)
 			{
 				Document *fdoc = DOCUMENT(documents[i]);
 
-				if (DOC_VALID(documents[i]) && GTK_IS_WIDGET(fdoc->tag_tree))
+				if (documents[i]->is_valid && GTK_IS_WIDGET(fdoc->tag_tree))
 					ui_widget_modify_font_from_string(fdoc->tag_tree,
 						interface_prefs.tagbar_font);
 			}
diff --git a/src/search.c b/src/search.c
index f68bd442..84438049 100644
--- a/src/search.c
+++ b/src/search.c
@@ -1407,7 +1407,7 @@ void search_find_usage(const gchar *search_text, gint flags, gboolean in_session
 		guint i;
 		for (i = 0; i < documents_array->len; i++)
 		{
-			if (DOC_VALID(documents[i]))
+			if (documents[i]->is_valid)
 				if (find_document_usage(documents[i], search_text, flags) > 0)
 					found = TRUE;
 		}
diff --git a/src/ui_utils.c b/src/ui_utils.c
index a5c631b2..9ae217da 100644
--- a/src/ui_utils.c
+++ b/src/ui_utils.c
@@ -555,7 +555,7 @@ void ui_save_buttons_toggle(gboolean enable)
 	{
 		/* check whether there are files where changes were made and if there are some,
 		 * we need the save all button / item */
-		if (DOC_VALID(documents[i]) && documents[i]->changed)
+		if (documents[i]->is_valid && documents[i]->changed)
 		{
 			dirty_tabs = TRUE;
 			break;