I saw X11 have some standard cursos missing on lib. So I create a invisible cursor and set it on my dialog and its works very well.
// 1 + 1 = transparent
// 0 + 0 = black
// 1 + 0 = white
// 0 + 1 = invert (on windows)
QImage imageBit(32,32, QImage::Format_Mono);
imageBit.fill(Qt::color0);
QImage imageMsk(32,32, QImage::Format_Mono);
imageMsk.fill(Qt::color1);
QBitmap bitmapBit = QBitmap::fromImage(imageBit);
QBitmap bitmapMsk = QBitmap::fromImage(imageMsk);
QCursor cursor = QCursor(bitmapBit, bitmapMsk, 47, 0);
this->setCursor(cursor);
I don't know if this problem is on this distribution of rasberry bullseye 64bits operational system only. But anyway, it is working now