Need help with slider widget

I am fairly new to Python and wxPython as well, I was making a music application recently using Tkinter, until recently I found out about wxPython, it seemed way flexible so I started trying it out, I am trying to reimplement my music application using wxPython and pygame, I made a slider widget to show current song position, like a seek bar, and I am using the timer widget to update it on per second basis, it works, it updates with time, but I cannot seem to scroll through the slider and change song position based on slider position, it does work, but I can’t seem to move it, it gets stuck when I click and try to drag to left or right…

Link to relevant part of code -

Please try to reproduce the problem in a small-as-possible standalone application. See this post for more info.