Description:
Trend lines in line charts are very helpful. But for the reader of a report/dashboard, it remains unclear what the grey line means and how the trend is calculated.
Current behaviour:
Lines charts allow to add trend lines, but the line chart is not able to provide a legend for the trend line.
How the feature should work:
If a trend line is added, show a legend for it, which includes the selected trend line calculation (when legends are enabled).
Why this is important:
Readers of the report should be able to easily understand the chart.