[Feature Request] Ability to set Border = false on ImageButtonWidget

### Related problem Buttons just below word "File" have border. I was able to remove border by adjusting Theme but then other buttons lost border too making them hard to identify as buttons. <img width="500" height="214" alt="Image" src="https://github.com/user-attachments/assets/2abf859a-25cb-4193-bf4c-7bfc00dd24a6" /> ### Your request Ability to have flat buttons (no border) without adjusting Theme for entire application and without affecting other widgets. ### Alternative solution _No response_ ### Additional context _No response_