Fix scrollbar render with RTL scroll following visible

Author: robob27

scene/gui/rich_text_label.cpp

@@ -2303,6 +2303,11 @@ RID RichTextLabel::get_focused_accessibility_element() const {
 	return get_accessibility_element();
 }
 
+void RichTextLabel::_prepare_scroll_anchor() {
+	scroll_w = vscroll->get_combined_minimum_size().width;
+	vscroll->set_anchor_and_offset(SIDE_LEFT, ANCHOR_END, -scroll_w);
+}
+
 void RichTextLabel::_notification(int p_what) {
 	switch (p_what) {
 		case NOTIFICATION_ACCESSIBILITY_INVALIDATE: {
@@ -2417,6 +2422,10 @@ void RichTextLabel::_notification(int p_what) {
 			queue_redraw();
 		} break;
 
+		case NOTIFICATION_READY: {
+			_prepare_scroll_anchor();
+		} break;
+
 		case NOTIFICATION_THEME_CHANGED: {
 			_stop_thread();
 			main->first_invalid_font_line.store(0); // Invalidate all lines.
@@ -2588,6 +2597,7 @@ void RichTextLabel::_notification(int p_what) {
 				from_line++;
 			}
 			if (scroll_follow_visible_characters && scroll_active) {
+				scroll_visible = follow_vc_pos > 0;
 				vscroll->set_visible(follow_vc_pos > 0);
 			}
 			if (has_focus() && get_tree()->is_accessibility_enabled()) {
@@ -3726,9 +3736,8 @@ _FORCE_INLINE_ float RichTextLabel::_update_scroll_exceeds(float p_total_height,
 	if (exceeds != scroll_visible) {
 		if (exceeds) {
 			scroll_visible = true;
-			scroll_w = vscroll->get_combined_minimum_size().width;
+			_prepare_scroll_anchor();
 			vscroll->show();
-			vscroll->set_anchor_and_offset(SIDE_LEFT, ANCHOR_END, -scroll_w);
 		} else {
 			scroll_visible = false;
 			scroll_w = 0;

scene/gui/rich_text_label.h

@@ -591,6 +591,8 @@ class RichTextLabel : public Control {
 	void _invalidate_accessibility();
 	void _invalidate_current_line(ItemFrame *p_frame);
 
+	void _prepare_scroll_anchor();
+
 	void _thread_function(void *p_userdata);
 	void _thread_end();
 	void _stop_thread();