add trace / update on Sliders on external variable change

[sayofan]

This one is pretty straightforward.

If the TkVar (I used IntVars) is changed from another widget, update the slider position.

This does not enforce the not-crossing-each-other on manipulations made by other widgets.
I tried to include that but it would only work if I define the code outside the RangedSlider.

It can, however be nicely done on the variables with something like for both the variables.

def check_limit_var_left(*args):
      update_val = hLeft.get()
      if update_val>hRight.get():
          hLeft.set(min(update_val, hRight.get()))

hLeft.trace_add("write", check_limit_var_left)