dropped features disappear from list after double klick

[g-rho]

repex:

task iris
select features -> uncheck petal.width, petal.length
click select
click select again -> features disappear from list and cannont be re-selected (unless a new task is created)

...repeat the same for sepal.width and sepal.length --> error due to non existing column(s)

[g-rho]

same for the positive class in german credit data: souble click on select (feature) removes selected class

[g-rho]

In addition: if you click 'deselect all' and confirm by clicking on 'Select' the screen will get transparent as a talk without features is not possible. In this case clicking 'Select' should not be possible but there should be a warning.