I have started to become interested in Black and white photographing. Exploring PhotoLab’s capacities for monochromatic editing, I found the Channel mixer (a Filmpack plug-in, if I remenber this correctly). This is very useful, for instance, for darkening the sky in a picture (blue slider), and the like. But what if you don’t want to apply the same change to every blue object you have in the picture (let’s say the sea)? As far as I can see, there is no way of doing local adjustments with the channel mixer (but correct me if I am wrong!). I think this feature would be quite useful.
(I suppose there might be some work-around for doing something in this direction I haven’t come up with.)
Converting to B&W can easily be done like shown here:
Using HSL’s pickup/dropper tool, you can select the colour and then widen or narrow the selected range by dragging the inner and outer handles in the HSL ring. Note that this procedure is a selective rather than a local adjustment possibility.
Also try the local adjustment “Control Line” tool. It might also do what you want, not by using the colour mixer, but the dropper tool and the sliders that already exist.
There are a lot of tools that would be useful as local adjustments but, in the past, there has been a lot of resistance against removing the equaliser from the local adjustment “marker” and moving those sliders to the sidebar.
There is no way tools like the colour wheel, channel mixer and other “large” tools can be accommodated other than in the sidebar.
You might like to search for existing posts on this kind of subject and add your votes there rather than starting yet another thread and diluting the vote pool.