The UCS Icon, Properties, File Tabs, and Layout Tabs buttons were highlighted unconditionally because their ids fell through to an active_tool equality check in is_active_tool, which activate_tool sets on every click and never clears. Each id is now mapped to its corresponding visibility flag (show_ucs_icon, show_properties, show_file_tabs, show_layout_tabs), and those flags are kept in sync from their toggle handlers so the highlight reflects live state. The per-toggle booleans previously threaded through the render path are consolidated into a single ToggleState struct read from one place, so introducing a further toggle no longer requires changing every render-function signature and call site.
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