Refactoring testing code and testing ui cancel buttons

- Test for cancel button behavior on dialogs
- Added select-menu and transition to tests
- Added specific dialogs and rearrangeed how they're setup and linked with menus (the menu item doesn't instantiate anymore, and, instead, just takes a reference).
- Refactored for clarity and abstracted:
  - About dialog
  - Ok-Cancel dialog
- Some follow-ups from previous PR

@devoncarew @dinhviethoa 
nit: indent