fix: Window Title Bar and Maximize Icon Not Updated Correctly When Restoring Maximized State via Code #1453

[Davidlegendre]

Pull request type

Please check the type of change your PR introduces:

• Update
• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes

What is the current behavior?

Currently, when a window is maximized programmatically (e.g., WindowState = Maximized in code), the title bar may not visually adjust correctly, and the client area does not provide appropriate padding. This results in content overlapping with the system-reserved areas (such as the taskbar or screen edges), and the maximize button may not reflect the correct state.

Issue Number: N/A

What is the new behavior?

• Title bar now visually updates correctly when the window is maximized via code.
• Proper padding is applied to the client area, ensuring that UI elements are not hidden or cut off at the edges.
• The maximize button reflects the correct state, even when maximized programmatically.
• Changes are encapsulated in ClientAreaBorder.cs for maintainability and clarity.

Other information

This fix ensures consistency between manual and programmatic window maximization. It improves UX for developers who customize their window behavior via code without relying on the user manually clicking the maximize button.

[kitgrose]

FYI, this PR isn't properly linked to the issue (#1453), because the issue number was used in the title but not in the text.