Take a look at how Rui does it. You create a widget through its parent:

   $label = $panel->Label(value => 'foo');              # is alias exi
+sts
   $label = $panel->Rui__Widget__Label(value => 'bar'); # if not
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It allows you to add aliases per project, solves the problem of the user having to set a parent on the child widget, allows you to change the real classes used for widgets in one place, and works with inheritance.

You want to look at Widget::Panel and Widget::Factory.