Now that we're working with all Ttk widgets, we can update our ValidatedMixin class with some dynamic styling.
We'll begin in the __init__() method by creating a Style object:
style = ttk.Style()
Since this is a mixin class, we don't know the original style name of the widget we're mixing with, so we'll have to fetch that.
Remember that we can do this with winfo_class():
widget_class = self.winfo_class()
validated_style = 'ValidatedInput.' + widget_class
After getting the widget class, we're creating a derivative style by prepending ValidatedInput to it. In order to toggle our input appearance between error and non-error appearances, we'll create a style map that switches with the state of the invalid state flag. ...
