Considering the scenario:

lineEdit->setValidator(new QIntValidator(10, 200, 0));
lineEdit->setInputMask("D90");
lineEdit->setText("99");

lineEdit->hasAcceptableInput() returns false although the third parameter in the mask is optional.
Seems the input mask "D90" forces a space to be added at the end of the string for values < 100 e.g. "99 " then QIntValidator parses the string and says the space is an invalid int char.
In qt3.3.3 the whitespace was stripped off before validation: