The x-tra.zip file you have requested: Tools and Utilities / StarEdit X-Tra Editor - 5.45mb is not available. Perhaps try browsing all files for the game StarCraft and upload any files you want to share or are missing. This is the only information we could locate:
This is an advanced map editor for StarCraft Brood War. It allows access to hidden triggers, treats buildings as no clip units (they can be stacked and such) and allow disabled units and stuff from StarCraft Beta and Alpha. This is an advanced map editor for StarCraft Brood War.