from traits.api import *
from traitsui.api import *
from traitsui.qt4.extra.bounds_editor import BoundsEditor


class Test(HasTraits):
    val = Range(0.3, 10.5)

    _xmin = Float(5.0)
    _xmax = Float(10.0)

    view = View(
        UItem(
            'val',
            editor=BoundsEditor(
                low_name='_xmin',
                high_name='_xmax',
                format='%.2f')
        )
    )

Test().configure_traits()

opt = QtGui.QStyleOptionSlider()
opt.sliderPosition = value

Python 3.9.10 (main, Mar  2 2022, 14:03:08) 
[GCC 11.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from pyface.qt import QtGui
>>> QtGui.QStyleOptionSlider().sliderValue = 5
>>> QtGui.QStyleOptionSlider().sliderValue = 5.5
<stdin>:1: DeprecationWarning: an integer is required (got type float).  Implicit conversion to integers using __int__ is deprecated, and may be removed in a future version of Python.

Python 3.10.2 (main, Jan 15 2022, 19:56:27) [GCC 11.1.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from pyface.qt import QtGui
>>> QtGui.QStyleOptionSlider().sliderValue = 5
>>> QtGui.QStyleOptionSlider().sliderValue = 5.5
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'float' object cannot be interpreted as an integer