ImU64   ImFileGetSize(ImFileHandle f)   { long off = 0, sz = 0; return ((off = ftell(f)) != -1 && !fseek(f, 0, SEEK_END) && (sz = ftell(f)) != -1 && !fseek(f, off, SEEK_SET)) ? (ImU64)sz : (ImU64)-1; }
