I have a configuration dialog that contains a percentage slider:
The user can set a range of 10% to 90% on this slider (don't ask why). In reality, the user is actually configuring a range with a 5% margin. So if the user sets the slider on 25%, in the background, the range is set to 20%-30%. The margin cannot be defined by the user.
I was wondering if I should inform the user that a margin is used instead of the specific percentage the user is configuring, and if yes how I should do this.
I was thinking of simply changing the percentage label behind the slider to 35% - 45% or highlighting a small area left and right of the slider handle like so:
or a combination of both.