Investigating reasons of fail FontTest tests i found bug in MultiCompositionScaner (or it maybe some related class). Looks like what Character value: 257 had a special meaning in squeak. If not use StrikeFont everything is well, but if you choose FreeType font the doing something (Character value: 257) asString asTextMorph openInWorld creates an endles loop in composer. It founds character falls in crossedX method (this character is stopCondition) and then remove character from composition and starts again.