I've already posted this in Questions & Feedback but since it doesn't seem to be implemented yet, I'm adding it as a request.
For example, I have a square which only has a fill color (no stroke).
If I click on another shape, let's say a circle and I'm changing it's stroke color, when I click back on the square, I would like the color panel to auto-select the fill attribute (since it's the only attribute the square has) instead of keeping the stroke attribute selected (from the previous change).
My logic is that I would want to change it's color rather than add a stroke to it. This way would eliminate an unnecessary extra click and speed you up when you'd have to repeat the action several times.