Fix TabBar initialization issue and add tests

scene/gui/tab_bar.cpp

@@ -354,6 +354,8 @@ void TabBar::_notification(int p_what) {
  if (scroll_to_selected) {
  ensure_tab_visible(current);
  }
+ // Set initialized even if no tabs were set.
+ initialized = true;
  } break;
 
  case NOTIFICATION_INTERNAL_PROCESS: {
@@ -655,10 +657,10 @@ void TabBar::set_tab_count(int p_count) {
  }
 
  if (!initialized) {
- if (queued_current != current) {
- current = queued_current;
- }
  initialized = true;
+ if (queued_current != CURRENT_TAB_UNINITIALIZED && queued_current != current) {
+ set_current_tab(queued_current);
+ }
  }
 
  queue_redraw();
@@ -740,6 +742,13 @@ bool TabBar::select_next_available() {
  return false;
 }
 
+void TabBar::set_tab_offset(int p_offset) {
+ ERR_FAIL_INDEX(p_offset, tabs.size());
+ offset = p_offset;
+ _update_cache();
+ queue_redraw();
+}
+
 int TabBar::get_tab_offset() const {
  return offset;
 }

scene/gui/tab_bar.h

@@ -117,8 +117,9 @@ class TabBar : public Control {
  bool scroll_to_selected = true;
  int tabs_rearrange_group = -1;
 
+ static const int CURRENT_TAB_UNINITIALIZED = -2;
  bool initialized = false;
- int queued_current = -1;
+ int queued_current = CURRENT_TAB_UNINITIALIZED;
 
  const float DEFAULT_GAMEPAD_EVENT_DELAY_MS = 0.5;
  const float GAMEPAD_EVENT_REPEAT_RATE_MS = 1.0 / 20;
@@ -249,6 +250,7 @@ class TabBar : public Control {
  bool select_previous_available();
  bool select_next_available();
 
+ void set_tab_offset(int p_offset);
  int get_tab_offset() const;
  bool get_offset_buttons_visible() const;
 

scene/gui/tab_container.cpp

@@ -190,7 +190,7 @@ void TabContainer::_notification(int p_what) {
  } break;
 
  case NOTIFICATION_VISIBILITY_CHANGED: {
- if (!is_visible() || setup_current_tab > -2) {
+ if (!is_visible()) {
  return;
  }
 
@@ -200,7 +200,7 @@ void TabContainer::_notification(int p_what) {
  // beat it to the punch and make sure that the correct node is the only one visible first.
  // Otherwise, it can prevent a tab change done right before this container was made visible.
  Vector<Control *> controls = _get_tab_controls();
- int current = get_current_tab();
+ int current = setup_current_tab > -2 ? setup_current_tab : get_current_tab();
  for (int i = 0; i < controls.size(); i++) {
  controls[i]->set_visible(i == current);
  }