This is a wishbug for adding shortcut of shift + Click on swatch for selecting background color in the palette docker. This will help in vector object workflow too. Where choosing the background color sets the stroke color of the vector object that is selected and clicking on the color swatch changes foreground color that is the fill color of the vector object selected.
I added rightclick selection of background color, based on the fact we use rightclick elsewhere to select background colors.
Thank you very much wolthera. Any shortcut is welcome, and your shortcut is correct.