Monthly summary for 2019-12 focused on delivering a performance-enhancing feature for OpenTTD/OpenTTD. Implemented Hotkey Navigation for Rail Type Selection in the Railway Build Toolbox, enabling quick cycling through rail types via keyboard shortcuts ( [ , ] , CTRL+[ , CTRL+] ), with the currently active toolbox widget preserved during changes. This supports power users utilizing PURR, Useless Tracks, U&ReRMM, and similar NewGRFs for faster, more accurate rail selection. The work is documented in commit 6cac80a1587e78143e076a0c695047f76ea8f892, detailing the support for next/prev/first/last railtype hotkeys and the preservation of toolbox state. Major bugs fixed: none documented for this month in the provided data. Overall impact: reduced build time and improved UX for rail-type selection, enabling more efficient gameplay and content creation. Technologies/skills demonstrated: keyboard event handling, UI state preservation, tool integration, support for modding workflows and NewGRFs, and cross-repo collaboration.