Implement tests for each bug/problem found for the Select component

[Andrevmatias]

The Combobox component must solve all the issues related to the Select component.

• [ ] Check all the related issues and implement unit tests for each of them:
  • [ ] #466
  • [x] #519
  • [ ] #520
  • [x] #532
  • [ ] #581
  • [x] #586
  • [x] #607
  • [x] #608
  • [x] #761
  • [x] #811