allow to change values when clicking on any part of the row

[antgonza]

Currently, for a user to change any values (color, scaling, opacity, etc) they need to click on the "value" side (left) of the row and it would be more convenient if it could be changed when the user clicks on any part of the row.

For example, in this menu, the selector is only shown when the user clicks on the left side of the table:

cc: @rob-knight