enhancement
The TabBar should be rendered using an HTML template, a ThemeVar.
Code Migration
Almost all configurable CSS classes for the DefaultTabBarRenderer have been removed. It is still possible to create a new type of tab bar. The "tab-bar-class" is still available for this purpose.
In addition, a new Java package named "layout.tabbar" has been created. All classes related to tabs were previously scattered across various packages in the project. All tab-related classes, except for TabComponent and the render classes, have been migrated to the new package.
Test
Start the application and verify that the tab bar functions exactly the same as it did before the refactoring.