Cypress' contains "can contain more than the desired text and still 
match". This creates issues when having similar names in 
dropdown-entries and unwanted elements get selected.

- Extract drop-list connection as separate utility function
- Add ID as optional parameter when adding lists. This can be used to 
improve readability of tests.
- some reordering of functions to make more sense.

Because there are more (pseudo-)tab on the (page-)tab pabel, the tab for 
the first page is no longer visible and can't be clicked. By increasing 
the viewport width, it becomes visible again.

It now always uses the old mode.

Expansion oanel seems not to render properly -  the last element is not 
there right away. A wait-command seems to help.

This is necessary now because mouseenter events are only handled when 
not already being over a list.

Add tests for buttons.

- Some very basic tests of creating an element and changing some 
properties
- Reference check for button with page navigation