Bring `TabBar` to full parity with the `TabContainer` implementation.

doc/classes/TabBar.xml

@@ -43,10 +43,11 @@
 				Returns the previously active tab index.
 			</description>
 		</method>
-		<method name="get_select_with_rmb" qualifiers="const">
-			<return type="bool" />
+		<method name="get_tab_button_icon" qualifiers="const">
+			<return type="Texture2D" />
+			<argument index="0" name="tab_idx" type="int" />
 			<description>
-				Returns [code]true[/code] if select with right mouse button is enabled.
+				Returns the [Texture2D] for the right button of the tab at index [code]tab_idx[/code] or [code]null[/code] if the button has no [Texture2D].
 			</description>
 		</method>
 		<method name="get_tab_icon" qualifiers="const">
@@ -111,6 +112,13 @@
 				Returns [code]true[/code] if the tab at index [code]tab_idx[/code] is disabled.
 			</description>
 		</method>
+		<method name="is_tab_hidden" qualifiers="const">
+			<return type="bool" />
+			<argument index="0" name="tab_idx" type="int" />
+			<description>
+				Returns [code]true[/code] if the tab at index [code]tab_idx[/code] is hidden.
+			</description>
+		</method>
 		<method name="move_tab">
 			<return type="void" />
 			<argument index="0" name="from" type="int" />
@@ -126,11 +134,12 @@
 				Removes the tab at index [code]tab_idx[/code].
 			</description>
 		</method>
-		<method name="set_select_with_rmb">
+		<method name="set_tab_button_icon">
 			<return type="void" />
-			<argument index="0" name="enabled" type="bool" />
+			<argument index="0" name="tab_idx" type="int" />
+			<argument index="1" name="icon" type="Texture2D" />
 			<description>
-				If [code]true[/code], enables selecting a tab with the right mouse button.
+				Sets an [code]icon[/code] for the button of the tab at index [code]tab_idx[/code] (located to the right, before the close button), making it visible and clickable (See [signal tab_button_pressed]). Giving it a [code]null[/code] value will hide the button.
 			</description>
 		</method>
 		<method name="set_tab_disabled">
@@ -141,6 +150,14 @@
 				If [code]disabled[/code] is [code]true[/code], disables the tab at index [code]tab_idx[/code], making it non-interactable.
 			</description>
 		</method>
+		<method name="set_tab_hidden">
+			<return type="void" />
+			<argument index="0" name="tab_idx" type="int" />
+			<argument index="1" name="hidden" type="bool" />
+			<description>
+				If [code]hidden[/code] is [code]true[/code], hides the tab at index [code]tab_idx[/code], making it disappear from the tab area.
+			</description>
+		</method>
 		<method name="set_tab_icon">
 			<return type="void" />
 			<argument index="0" name="tab_idx" type="int" />
@@ -200,10 +217,17 @@
 		<member name="drag_to_rearrange_enabled" type="bool" setter="set_drag_to_rearrange_enabled" getter="get_drag_to_rearrange_enabled" default="false">
 			If [code]true[/code], tabs can be rearranged with mouse drag.
 		</member>
+		<member name="scroll_to_selected" type="bool" setter="set_scroll_to_selected" getter="get_scroll_to_selected" default="true">
+			If [code]true[/code], the tab offset will be changed to keep the the currently selected tab visible.
+		</member>
 		<member name="scrolling_enabled" type="bool" setter="set_scrolling_enabled" getter="get_scrolling_enabled" default="true">
 			if [code]true[/code], the mouse's scroll wheel can be used to navigate the scroll view.
 		</member>
+		<member name="select_with_rmb" type="bool" setter="set_select_with_rmb" getter="get_select_with_rmb" default="false">
+			If [code]true[/code], enables selecting a tab with the right mouse button.
+		</member>
 		<member name="tab_alignment" type="int" setter="set_tab_alignment" getter="get_tab_alignment" enum="TabBar.AlignmentMode" default="1">
+			Sets the position at which tabs will be placed. See [enum AlignmentMode] for details.
 		</member>
 		<member name="tab_close_display_policy" type="int" setter="set_tab_close_display_policy" getter="get_tab_close_display_policy" enum="TabBar.CloseButtonDisplayPolicy" default="0">
 			Sets when the close button will appear on the tabs. See [enum CloseButtonDisplayPolicy] for details.
@@ -219,6 +243,12 @@
 				Emitted when the active tab is rearranged via mouse drag. See [member drag_to_rearrange_enabled].
 			</description>
 		</signal>
+		<signal name="tab_button_pressed">
+			<argument index="0" name="tab" type="int" />
+			<description>
+				Emitted when a tab's right button is pressed. See [method set_tab_button_icon].
+			</description>
+		</signal>
 		<signal name="tab_changed">
 			<argument index="0" name="tab" type="int" />
 			<description>
@@ -255,18 +285,28 @@
 		<signal name="tab_rmb_clicked">
 			<argument index="0" name="tab" type="int" />
 			<description>
-				Emitted when a tab is right-clicked.
+				Emitted when a tab is right-clicked. [member select_with_rmb] must be enabled.
+			</description>
+		</signal>
+		<signal name="tab_selected">
+			<argument index="0" name="tab" type="int" />
+			<description>
+				Emitted when a tab is selected via click or script, even if it is the current tab.
 			</description>
 		</signal>
 	</signals>
 	<constants>
 		<constant name="ALIGNMENT_LEFT" value="0" enum="AlignmentMode">
+			Places tabs to the left.
 		</constant>
 		<constant name="ALIGNMENT_CENTER" value="1" enum="AlignmentMode">
+			Places tabs in the middle.
 		</constant>
 		<constant name="ALIGNMENT_RIGHT" value="2" enum="AlignmentMode">
+			Places tabs to the right.
 		</constant>
 		<constant name="ALIGNMENT_MAX" value="3" enum="AlignmentMode">
+			Represents the size of the [enum AlignmentMode] enum.
 		</constant>
 		<constant name="CLOSE_BUTTON_SHOW_NEVER" value="0" enum="CloseButtonDisplayPolicy">
 			Never show the close buttons.
@@ -321,11 +361,11 @@
 		<theme_item name="increment_highlight" data_type="icon" type="Texture2D">
 			Icon for the right arrow button that appears when there are too many tabs to fit in the container width. Used when the button is being hovered with the cursor.
 		</theme_item>
-		<theme_item name="close_bg_highlight" data_type="style" type="StyleBox">
-			Background of the close button when it's being hovered with the cursor.
+		<theme_item name="button_highlight" data_type="style" type="StyleBox">
+			Background of the tab and close buttons when they're being hovered with the cursor.
 		</theme_item>
-		<theme_item name="close_bg_pressed" data_type="style" type="StyleBox">
-			Background of the close button when it's being pressed.
+		<theme_item name="button_pressed" data_type="style" type="StyleBox">
+			Background of the tab and close buttons when it's being pressed.
 		</theme_item>
 		<theme_item name="tab_disabled" data_type="style" type="StyleBox">
 			The style of disabled tabs.

editor/editor_node.cpp

@@ -340,7 +340,7 @@ void EditorNode::_update_scene_tabs() {
 		}
 
 		if (show_rb && editor_data.get_scene_root_script(i).is_valid()) {
-			scene_tabs->set_tab_right_button(i, script_icon);
+			scene_tabs->set_tab_button_icon(i, script_icon);
 		}
 	}
 
@@ -6233,7 +6233,7 @@ EditorNode::EditorNode() {
 	scene_tabs->set_min_width(int(EDITOR_DEF("interface/scene_tabs/minimum_width", 50)) * EDSCALE);
 	scene_tabs->set_drag_to_rearrange_enabled(true);
 	scene_tabs->connect("tab_changed", callable_mp(this, &EditorNode::_scene_tab_changed));
-	scene_tabs->connect("tab_rmb_clicked", callable_mp(this, &EditorNode::_scene_tab_script_edited));
+	scene_tabs->connect("tab_button_pressed", callable_mp(this, &EditorNode::_scene_tab_script_edited));
 	scene_tabs->connect("tab_close_pressed", callable_mp(this, &EditorNode::_scene_tab_closed), varray(SCENE_TAB_CLOSE));
 	scene_tabs->connect("tab_hovered", callable_mp(this, &EditorNode::_scene_tab_hovered));
 	scene_tabs->connect("mouse_exited", callable_mp(this, &EditorNode::_scene_tab_exit));

editor/editor_themes.cpp

@@ -1016,8 +1016,8 @@ Ref<Theme> create_editor_theme(const Ref<Theme> p_theme) {
 	theme->set_stylebox("SceneTabFG", "EditorStyles", style_tab_selected);
 	theme->set_stylebox("SceneTabBG", "EditorStyles", style_tab_unselected);
 	theme->set_icon("close", "TabBar", theme->get_icon("GuiClose", "EditorIcons"));
-	theme->set_stylebox("close_bg_pressed", "TabBar", style_menu);
-	theme->set_stylebox("close_bg_highlight", "TabBar", style_menu);
+	theme->set_stylebox("button_pressed", "TabBar", style_menu);
+	theme->set_stylebox("button_highlight", "TabBar", style_menu);
 	theme->set_icon("increment", "TabContainer", theme->get_icon("GuiScrollArrowRight", "EditorIcons"));
 	theme->set_icon("decrement", "TabContainer", theme->get_icon("GuiScrollArrowLeft", "EditorIcons"));
 	theme->set_icon("increment", "TabBar", theme->get_icon("GuiScrollArrowRight", "EditorIcons"));

editor/plugins/theme_editor_plugin.cpp

@@ -3469,7 +3469,7 @@ void ThemeEditor::_add_preview_tab(ThemeEditorPreview *p_preview_tab, const Stri
 
 	preview_tabs->add_tab(p_preview_name, p_icon);
 	preview_tabs_content->add_child(p_preview_tab);
-	preview_tabs->set_tab_right_button(preview_tabs->get_tab_count() - 1, EditorNode::get_singleton()->get_gui_base()->get_theme_icon(SNAME("close"), SNAME("TabBar")));
+	preview_tabs->set_tab_button_icon(preview_tabs->get_tab_count() - 1, EditorNode::get_singleton()->get_gui_base()->get_theme_icon(SNAME("close"), SNAME("TabBar")));
 	p_preview_tab->connect("control_picked", callable_mp(this, &ThemeEditor::_preview_control_picked));
 
 	preview_tabs->set_current_tab(preview_tabs->get_tab_count() - 1);
@@ -3600,7 +3600,7 @@ ThemeEditor::ThemeEditor() {
 	preview_tabs->set_h_size_flags(SIZE_EXPAND_FILL);
 	preview_tabbar_hb->add_child(preview_tabs);
 	preview_tabs->connect("tab_changed", callable_mp(this, &ThemeEditor::_change_preview_tab));
-	preview_tabs->connect("tab_rmb_clicked", callable_mp(this, &ThemeEditor::_remove_preview_tab));
+	preview_tabs->connect("tab_button_pressed", callable_mp(this, &ThemeEditor::_remove_preview_tab));
 
 	HBoxContainer *add_preview_button_hb = memnew(HBoxContainer);
 	preview_tabbar_hb->add_child(add_preview_button_hb);

scene/gui/tab_bar.h

@@ -63,12 +63,11 @@ private:
 
 		Ref<TextLine> text_buf;
 		Ref<Texture2D> icon;
-		int ofs_cache = 0;
 		bool disabled = false;
+		bool hidden = false;
+		int ofs_cache = 0;
 		int size_cache = 0;
 		int size_text = 0;
-		int x_cache = 0;
-		int x_size_cache = 0;
 
 		Ref<Texture2D> right_button;
 		Rect2 rb_rect;
@@ -102,6 +101,7 @@ private:
 	int min_width = 0;
 	bool scrolling_enabled = true;
 	bool drag_to_rearrange_enabled = false;
+	bool scroll_to_selected = true;
 	int tabs_rearrange_group = -1;
 
 	int get_tab_width(int p_idx) const;
@@ -150,8 +150,11 @@ public:
 	void set_tab_disabled(int p_tab, bool p_disabled);
 	bool is_tab_disabled(int p_tab) const;
 
-	void set_tab_right_button(int p_tab, const Ref<Texture2D> &p_right_button);
-	Ref<Texture2D> get_tab_right_button(int p_tab) const;
+	void set_tab_hidden(int p_tab, bool p_hidden);
+	bool is_tab_hidden(int p_tab) const;
+
+	void set_tab_button_icon(int p_tab, const Ref<Texture2D> &p_icon);
+	Ref<Texture2D> get_tab_button_icon(int p_tab) const;
 
 	void set_tab_alignment(AlignmentMode p_alignment);
 	AlignmentMode get_tab_alignment() const;
@@ -187,6 +190,9 @@ public:
 	void set_tabs_rearrange_group(int p_group_id);
 	int get_tabs_rearrange_group() const;
 
+	void set_scroll_to_selected(bool p_enabled);
+	bool get_scroll_to_selected() const;
+
 	void set_select_with_rmb(bool p_enabled);
 	bool get_select_with_rmb() const;
 

scene/resources/default_theme/default_theme.cpp

@@ -817,8 +817,8 @@ void fill_default_theme(Ref<Theme> &theme, const Ref<Font> &default_font, Ref<Te
 	theme->set_stylebox("tab_selected", "TabBar", style_tab_selected);
 	theme->set_stylebox("tab_unselected", "TabBar", style_tab_unselected);
 	theme->set_stylebox("tab_disabled", "TabBar", style_tab_disabled);
-	theme->set_stylebox("close_bg_pressed", "TabBar", button_pressed);
-	theme->set_stylebox("close_bg_highlight", "TabBar", button_normal);
+	theme->set_stylebox("button_pressed", "TabBar", button_pressed);
+	theme->set_stylebox("button_highlight", "TabBar", button_normal);
 
 	theme->set_icon("increment", "TabBar", icons["scroll_button_right"]);
 	theme->set_icon("increment_highlight", "TabBar", icons["scroll_button_right_hl"]);