On Linux the window always had no OS decorations and drew Windows-style caption buttons in the application bar. SOLIDCRAFT_TITLEBAR=system, or "titlebar": "system" in graphics.json, now opens the window with the desktop's own title bar and buttons (server-side decorations where the compositor offers them). The default is unchanged; Windows and macOS are unaffected. Claude-Session: https://claude.ai/code/session_01Gnm1n2PVPqghMuR9kHWXfh Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>