Sometimes you are searching for a value that resides between two numbers that are very far apart, such as 0 and 1,000,000. Stepping through each of those values one by one would be tedious. You can change the step value of the displayed number using the -resolution option. The default for -resolution is 1, but it can be changed to any value that is less or greater than that.
Note that if the resolution is larger than 1, it is possible for the slider to have a value (set by the program, for example) that is smaller or larger than the displayed value.