Bug: manual slope selection plot does not update if selected point is before current slope

[js3110]

Description

When a manual slope selection is added, the plot only updates if the point selected is > time than the previous selection, otherwise it doesn't update visually. In the NCA results and in the table everything is fine, it is just the visuals of the plot.

To reproduce

Run NCA -> Slope selector -> select a point that is before the current slope (black) and then click the end point. The black point selected does not turn green.

Expected behaviour

The black point selected should turn green and be included in the line of best fit

[Gero1999]

regarding this for whenever is taken care I would recommend to look first at how the index column (IX) is being created and how the lambda_plot is filtering them based on lambda.z.time.first! Changes in the app could have compromised the process and pass unnoticed