The former solution was affecting the selection CSS of the button. Now 
the text is moved down instead.

#562

#542

The directive for dynamic backgroudn color was outdated. Directive is 
removed and problem is solved via CSS custom variable.

#561

#449

- position
- label
- icon

Was completely broken: not showing at all in Editor, not clickable in 
Player.

Removed pipe 'aspectInputBackgroundColor'. Replaced by more elegant 
solution via inherited background-color.

THis component was still somewhat broken after the Material update.

#541

#545

The inclusion of svg icons via the src parameter of an image tag
is prohibited in the test centre for security reasons

- Remove all Roboto files

Since there is just one font, this setting can be safely ignored. This 
is easier than sanitizing all elements.

#513

#499
- Problem was due to changes in the latest minor material update

#533
- Remove unnecessary and wrong setting of underline property

#531

#532
- Replace the global label identifier

#535

#454
- does not work in FF

#456

- Add Property "hasAutoHeight"
- Add Directive AutoHeight

#520

Make player control bar inherit pointer-event styling. This way the 
Editor can set it to none, while acting normal in the Player.

#524

- Don't report empty reference string as invalid
- Add VideoElements to check

Absolute position didn't work if the display scaling factor of the
operating system or browser is not 1.

#511

- crossOutChecked adds line-through styling if checked. This is used in 
Cloze texts to cross out words.
- This means Checkbox is no longer a PositionedElement and does not 
validate PositionProperties

#521

#521

#521

#521

- Replace or remove no longer used material customization

#521

- Remove no longer used material customization

#513

- Can also be used with other elements