Inkscape 1.0rc1 (09960d6, 2020-04-09): Blur buttons in Fill and Stroke not working properly

Steps to reproduce:

– Launch Inkscape 1.0rc1 (09960d6, 2020-04-09) – create a line with the Bezier tool – open Fill and Stroke

What happened?

The Blur slide at the bottom has an up "^" and down "v" arrow. Both arrows increase the Blur.

What should have happened?

I would expect the up arrow to increase Blur, and the down one to decrease it. But clicking on either just keeps on increasing Blur in 1.0 steps.

Note: The manual, horizontal slider works fine.

Inkscape Version and Operating System:

• Inkscape Version: 1.0rc1 (09960d6, 2020-04-09)
• Operating System: Windows 7 32-bit