Most suitable widget for real numbers

[Rich Shepard]

Looking at lists of PyQt widgets I don't find one for real numbers, such as
chemical concentrations. The QSpinBox appears to accept only integers and
QTextEdit might work if I set validations to accept only digits with a
single decimal point for fractions.

My applications have to accommodate numerous real numbers. In addition to
concentrations (which cannot be negative) there are width and depth,
velocity and quantity, etc. I need to learn how best to accomodate these
values and I look forward to learning how to include them.

Rich