Hard to set exact brightness for flat box

I have Alnitak compatible light box using SGP
On the other control Panel, it very difficult to set a precise value for the brightness by dragging the brightness control. Having a text box or a spin control to enter an exact value would be a great improvement.

Click on the drag control and drag it to near the position you want (or just click it and don’t drag anywhere), then, using the left and right arrow keys, you can make precision adjustments.