Fix debugger behaviour with multi-session debugging:

Fixes script editor debug menu on sessions other than 1
Fixes breakpoint toggle from menu in sessions other than 1
Removes execution display when switching to non-breaked sessions

editor/debugger/editor_debugger_node.cpp

@@ -107,6 +107,8 @@ ScriptEditorDebugger *EditorDebuggerNode::_add_debugger() {
 	node->connect("remote_object_updated", callable_mp(this, &EditorDebuggerNode::_remote_object_updated).bind(id));
 	node->connect("remote_object_property_updated", callable_mp(this, &EditorDebuggerNode::_remote_object_property_updated).bind(id));
 	node->connect("remote_object_requested", callable_mp(this, &EditorDebuggerNode::_remote_object_requested).bind(id));
+	node->connect("set_breakpoint", callable_mp(this, &EditorDebuggerNode::_breakpoint_set_in_tree).bind(id));
+	node->connect("clear_breakpoints", callable_mp(this, &EditorDebuggerNode::_breakpoints_cleared_in_tree).bind(id));
 	node->connect("errors_cleared", callable_mp(this, &EditorDebuggerNode::_update_errors));
 
 	if (tabs->get_tab_count() > 0) {
@@ -168,6 +170,27 @@ void EditorDebuggerNode::_text_editor_stack_goto(const ScriptEditorDebugger *p_d
 	stack_script.unref(); // Why?!?
 }
 
+void EditorDebuggerNode::_text_editor_stack_clear(const ScriptEditorDebugger *p_debugger) {
+	String file = p_debugger->get_stack_script_file();
+	if (file.is_empty()) {
+		return;
+	}
+	if (file.is_resource_file()) {
+		stack_script = ResourceLoader::load(file);
+	} else {
+		// If the script is built-in, it can be opened only if the scene is loaded in memory.
+		int i = file.find("::");
+		int j = file.rfind("(", i);
+		if (j > -1) { // If the script is named, the string is "name (file)", so we need to extract the path.
+			file = file.substr(j + 1, file.find(")", i) - j - 1);
+		}
+		Ref<PackedScene> ps = ResourceLoader::load(file.get_slice("::", 0));
+		stack_script = ResourceLoader::load(file);
+	}
+	emit_signal(SNAME("clear_execution"), stack_script);
+	stack_script.unref(); // Why?!?
+}
+
 void EditorDebuggerNode::_bind_methods() {
 	// LiveDebug.
 	ClassDB::bind_method("live_debug_create_node", &EditorDebuggerNode::live_debug_create_node);
@@ -183,6 +206,8 @@ void EditorDebuggerNode::_bind_methods() {
 	ADD_SIGNAL(MethodInfo("clear_execution", PropertyInfo("script")));
 	ADD_SIGNAL(MethodInfo("breaked", PropertyInfo(Variant::BOOL, "reallydid"), PropertyInfo(Variant::BOOL, "can_debug")));
 	ADD_SIGNAL(MethodInfo("breakpoint_toggled", PropertyInfo(Variant::STRING, "path"), PropertyInfo(Variant::INT, "line"), PropertyInfo(Variant::BOOL, "enabled")));
+	ADD_SIGNAL(MethodInfo("breakpoint_set_in_tree", PropertyInfo("script"), PropertyInfo(Variant::INT, "line"), PropertyInfo(Variant::BOOL, "enabled"), PropertyInfo(Variant::INT, "debugger")));
+	ADD_SIGNAL(MethodInfo("breakpoints_cleared_in_tree", PropertyInfo(Variant::INT, "debugger")));
 }
 
 void EditorDebuggerNode::register_undo_redo(UndoRedo *p_undo_redo) {
@@ -198,6 +223,10 @@ ScriptEditorDebugger *EditorDebuggerNode::get_debugger(int p_id) const {
 	return Object::cast_to<ScriptEditorDebugger>(tabs->get_tab_control(p_id));
 }
 
+ScriptEditorDebugger *EditorDebuggerNode::get_previous_debugger() const {
+	return Object::cast_to<ScriptEditorDebugger>(tabs->get_tab_control(tabs->get_previous_tab()));
+}
+
 ScriptEditorDebugger *EditorDebuggerNode::get_current_debugger() const {
 	return Object::cast_to<ScriptEditorDebugger>(tabs->get_tab_control(tabs->get_current_tab()));
 }
@@ -436,12 +465,18 @@ void EditorDebuggerNode::_debugger_changed(int p_tab) {
 		// Hopefully, in the future, we will have one inspector per debugger.
 		EditorNode::get_singleton()->push_item(nullptr);
 	}
+
+	if (get_previous_debugger()) {
+		_text_editor_stack_clear(get_previous_debugger());
+	}
 	if (remote_scene_tree->is_visible_in_tree()) {
 		get_current_debugger()->request_remote_tree();
 	}
 	if (get_current_debugger()->is_breaked()) {
 		_text_editor_stack_goto(get_current_debugger());
 	}
+
+	_break_state_changed();
 }
 
 void EditorDebuggerNode::set_script_debug_button(MenuButton *p_button) {
@@ -533,7 +568,7 @@ void EditorDebuggerNode::_breaked(bool p_breaked, bool p_can_debug, String p_mes
 }
 
 bool EditorDebuggerNode::is_skip_breakpoints() const {
-	return get_default_debugger()->is_skip_breakpoints();
+	return get_current_debugger()->is_skip_breakpoints();
 }
 
 void EditorDebuggerNode::set_breakpoint(const String &p_path, int p_line, bool p_enabled) {
@@ -565,23 +600,23 @@ void EditorDebuggerNode::reload_scripts() {
 }
 
 void EditorDebuggerNode::debug_next() {
-	get_default_debugger()->debug_next();
+	get_current_debugger()->debug_next();
 }
 
 void EditorDebuggerNode::debug_step() {
-	get_default_debugger()->debug_step();
+	get_current_debugger()->debug_step();
 }
 
 void EditorDebuggerNode::debug_break() {
-	get_default_debugger()->debug_break();
+	get_current_debugger()->debug_break();
 }
 
 void EditorDebuggerNode::debug_continue() {
-	get_default_debugger()->debug_continue();
+	get_current_debugger()->debug_continue();
 }
 
 String EditorDebuggerNode::get_var_value(const String &p_var) const {
-	return get_default_debugger()->get_var_value(p_var);
+	return get_current_debugger()->get_var_value(p_var);
 }
 
 // LiveEdit/Inspector
@@ -655,6 +690,22 @@ void EditorDebuggerNode::_save_node_requested(ObjectID p_id, const String &p_fil
 	get_current_debugger()->save_node(p_id, p_file);
 }
 
+void EditorDebuggerNode::_breakpoint_set_in_tree(Ref<RefCounted> p_script, int p_line, bool p_enabled, int p_debugger) {
+	if (p_debugger != tabs->get_current_tab()) {
+		return;
+	}
+
+	emit_signal(SNAME("breakpoint_set_in_tree"), p_script, p_line, p_enabled);
+}
+
+void EditorDebuggerNode::_breakpoints_cleared_in_tree(int p_debugger) {
+	if (p_debugger != tabs->get_current_tab()) {
+		return;
+	}
+
+	emit_signal(SNAME("breakpoints_cleared_in_tree"));
+}
+
 // Remote inspector/edit.
 void EditorDebuggerNode::_method_changeds(void *p_ud, Object *p_base, const StringName &p_name, const Variant **p_args, int p_argcount) {
 	if (!singleton) {

editor/debugger/editor_debugger_node.h

@@ -138,11 +138,15 @@ protected:
 	void _remote_object_requested(ObjectID p_id, int p_debugger);
 	void _save_node_requested(ObjectID p_id, const String &p_file, int p_debugger);
 
+	void _breakpoint_set_in_tree(Ref<RefCounted> p_script, int p_line, bool p_enabled, int p_debugger);
+	void _breakpoints_cleared_in_tree(int p_debugger);
+
 	void _clear_execution(Ref<RefCounted> p_script) {
 		emit_signal(SNAME("clear_execution"), p_script);
 	}
 
 	void _text_editor_stack_goto(const ScriptEditorDebugger *p_debugger);
+	void _text_editor_stack_clear(const ScriptEditorDebugger *p_debugger);
 	void _stack_frame_selected(int p_debugger);
 	void _error_selected(const String &p_file, int p_line, int p_debugger);
 	void _breaked(bool p_breaked, bool p_can_debug, String p_message, bool p_has_stackdump, int p_debugger);
@@ -159,6 +163,7 @@ public:
 	static EditorDebuggerNode *get_singleton() { return singleton; }
 	void register_undo_redo(UndoRedo *p_undo_redo);
 
+	ScriptEditorDebugger *get_previous_debugger() const;
 	ScriptEditorDebugger *get_current_debugger() const;
 	ScriptEditorDebugger *get_default_debugger() const;
 	ScriptEditorDebugger *get_debugger(int p_debugger) const;

editor/plugins/script_editor_plugin.cpp

@@ -4009,8 +4009,8 @@ ScriptEditor::ScriptEditor(WindowWrapper *p_wrapper) {
 	debugger->connect("set_execution", callable_mp(this, &ScriptEditor::_set_execution));
 	debugger->connect("clear_execution", callable_mp(this, &ScriptEditor::_clear_execution));
 	debugger->connect("breaked", callable_mp(this, &ScriptEditor::_breaked));
-	debugger->get_default_debugger()->connect("set_breakpoint", callable_mp(this, &ScriptEditor::_set_breakpoint));
-	debugger->get_default_debugger()->connect("clear_breakpoints", callable_mp(this, &ScriptEditor::_clear_breakpoints));
+	debugger->connect("breakpoint_set_in_tree", callable_mp(this, &ScriptEditor::_set_breakpoint));
+	debugger->connect("breakpoints_cleared_in_tree", callable_mp(this, &ScriptEditor::_clear_breakpoints));
 
 	menu_hb->add_spacer();