updates an existing preview file for this item. pszPreviewFile points to local file, which must be under 1MB in size
public static bool UpdateItemPreviewFile(UGCUpdateHandle_t handle, uint index, string pszPreviewFile) { InteropHelp.TestIfAvailableGameServer(); using (var pszPreviewFile2 = new InteropHelp.UTF8StringHandle(pszPreviewFile)) { return NativeMethods.ISteamGameServerUGC_UpdateItemPreviewFile(handle, index, pszPreviewFile2); } }