问题 What is the maximum value of QSlider, in the datasheet, it is just mentioned as int. I tried with "1000000". but the Slider starts bugging. QSlider.setMaximum(1000000); Image with the bug, the blue color and the cursor don't move well at same speed, if the number is at max : 999999999, the cursor don't move at all. when I put : max at : 650000 that works very well. That is perhaps an OS problem, I am using IOS.. By the way, here is an update of code, works fine with 100000 x 2 possible values