I would like to shade under a line on one of my charts. This shading should cover all area below the line, is there an expression I can use within the 'Background Color' option of my line expression?
You can use a different style. Go to Properties>Style, there you can choose several different styles.
Choose one of the two at the bottom. It will achieve what you want.
Oh, sorry, this works only by line chart type. Combo chart doesn't have this option.
Retrieving data ...