Apologies if this is a known issue:
As of what appears to be Kendo UI 2017 R3 SP1, the horizontal scrollbar doesn't behave like it used to. Using the following example:
If I choose Kendo UI 2017 R3 from the Library dropdown, run the example, and click on the empty space to the right of the horizontal scrollbar, it moves to the far right of the grid with one click.
If I choose any version after Kendo UI 2017 R3 (including the latest 2018 R1 version), I have to click multiple times to get the scrollbar to move just a fraction of the grid's width.
I've tested this in IE and Opera browsers and found the same results.