Bug fixes and refactoring

• Removed redundant exception that caused warning on some compilers.
• Made vertical scrollbar adjust max automatically by default.
• Fixed vertical scrollbar with global scale.
• Refactored panel tabs - fixed bugs and made cleaner code (note: this slightly change their behavior).
• Optimized getting sorted children list - less garbage and sorting per frame.
• Refactored panels with scrollbar implementation - fixed bugs and made cleaner code.