What Application are you using?
Designer / Photo / Publisher
Are you using the latest release version?
v2.1.1
Can you reproduce it?
Yes
Does it happen for a new document? If not can you upload a document that shows the problem?
Yes
hardware acceleration
Same issue with both.
What happened for you (and what you expected to happen)
Using the scroll wheel on the start and end arrowhead size does not update anything apart from the text in the field that you are scrolling in ._.