Initial state "no value" #970
Description
What I am missing is a state, where the slider has no value yet. This is needed, when you need to collect a value from the user and only from the user rather than a default value.
The handle should indicate (eg. by color), that it is in the state of no value, so that the user can see, whether he needs to set a value or not. As soon as the user moves the handle, it should change its color. Same with the slider-selection - it should indicate a state of no value (not filled, when a color indicates "how much").
The initial position of the handle can be in the minimum position or in a neutral position (in the middle). Both options can be useful depending from what is required.