I recently started using a Bluetooth keyboard when drawing/painting. Its great! However, In the manual there is a section of keyboard shortcuts called 'additional shortcuts' where brush size and other parameters can be set with 'held' key combos such as ctrl+option, but that section isn't in ArtStudioPro editor.
Since it is now in gestures section rather than the shortcut editor, I guess its not possible to customize it, but it would be great if that were an option. I'd like to have single key for changing the size as its much easier than having to holding down two.