As a user, I want to customise a window’s appearance and behaviour through the API so that I can tailor windows to my application’s needs.

[benofthebens]

Acceptance Criteria

Window Appearance Options

• Window has configurable title bar visibility (shown/hidden)
• Window has configurable border visibility
• Window supports configurable transparency/opacity
• Window background colour can be set
• Window can be fixed size or auto-sized

Window Behaviour Options

• Window can be set as resizable or non-resizable
• Minimise/maximise behaviour can be allowed or disallowed
• Always-on-top option is available
• Closing the window triggers destruction or a callback
• Window can start focused or unfocused

API Reliability Requirements

• API correctly applies different combinations of flags and properties
• API handles invalid or unsupported configurations gracefully, returning a clear error
• Repeated creation and destruction of windows does not leak memory or resources