When a control such as a tab or a combobox is focused, it darkens to a dark grey color. How can we set that color that a control changes to when focused? I have had a good look around at the different options but can't seem to find anything.

you'll need to override virtual draw method and do custom drawing
please check tutorial

I considered doing this, however the tutorials don't show how to draw the control the same way. I'm very happy with the way the controls are drawn by default, I just want to change that darkening.

Can you show an example of the button drawing code of how it is currently drawn, so that we can mimic that in our override control in order to keep the same drawing behaviour, but just change the focused color?

I can consider adding source for Button::draw into the personal license