To operate on a slider object and based on your requirement, you can use any of these functions
decrease - Decrease the slider
increase - Increase the slider
setmax - Set the slider to max value
setmin - Set the slider to min value
verifyslider - Verify whether the object is slider
verifysliderhorizontal - Verify whether the object is horizontal slider
verifyslidervertical - Verify whether the object is vertical slider
Linux Desktop Testing Project