I recently purchased Affinity Publisher and Designer for macOS (after previously purchasing Affinity Photo in December 2019) and this feature request relates to all three products.
All three products have the Transform panel which allows users to easily adjust values for moving, resizing etc. One thing I keep wanting to do is to click on a little arrow to increment the value for fine tuning.
For example, in the mock-up below I show both the current design of the Transform panel and what I'm proposing. Currently, if I want to change the X value from -125.4 to -125.3, I have to click the field to highlight it, click again to place the cursor after the '4', press the delete key and then entire the value '3' followed by pressing Enter. However, in the proposed state, I could just click on the down arrow to change the X value by one increment from -125.4 to -125.3.
In other words, currently I need to do two clicks and three keyboard presses. In the proposed state this would just be one click.
Finally, using arrows is much better from the point of view of comparing the impacts of the change, as I can view the change in real time as I'm clicking up/down.