HackStudio: Update the window title after changing an active editor

Prior this change, the window title was updated only when a new file
has been opened, which means that it wasn't updated when user selected
an already opened file in the split view.

This change updates the title whenever the active editor changes.
In addition, this title update logic has now its own function
as it'll also be used in the next commit. :)

Userland/DevTools/HackStudio/HackStudioWidget.cpp

@@ -288,7 +288,6 @@ bool HackStudioWidget::open_file(const String& full_filename)
     if (filename.starts_with(m_project->root_path()))
         relative_file_path = filename.substring(m_project->root_path().length() + 1);
 
-    window()->set_title(String::formatted("{} - {} - Hack Studio", relative_file_path, m_project->name()));
     m_project_tree_view->update();
 
     current_editor_wrapper().set_filename(filename);
@@ -826,6 +825,7 @@ Project& HackStudioWidget::project()
 void HackStudioWidget::set_current_editor_wrapper(RefPtr<EditorWrapper> editor_wrapper)
 {
     m_current_editor_wrapper = editor_wrapper;
+    update_window_title();
 }
 
 void HackStudioWidget::configure_project_tree_view()
@@ -1194,4 +1194,9 @@ void HackStudioWidget::update_gml_preview()
     m_gml_preview_widget->load_gml(gml_content);
 }
 
+void HackStudioWidget::update_window_title()
+{
+    window()->set_title(String::formatted("{} - {} - Hack Studio", m_current_editor_wrapper->filename_label().text(), m_project->name()));
+}
+
 }

Userland/DevTools/HackStudio/HackStudioWidget.h

@@ -122,6 +122,7 @@ private:
     bool any_document_is_dirty() const;
 
     void update_gml_preview();
+    void update_window_title();
 
     NonnullRefPtrVector<EditorWrapper> m_all_editor_wrappers;
     RefPtr<EditorWrapper> m_current_editor_wrapper;