We are a bit limited in what we can do here. We rely at the Blender UI solution. What you suggest is not completely impossible, but just possible to some degree. A very small degree unfortunately. And so the very most Blender themes have the same behaviour here.
You could try another theme, and check if that fits your needs better. Every Blender theme works also in Bforartists. And can be chosen and installed in the User Preferences in the Themes tab. But they all have the same problem than the Bforartists standard theme.