Hi!

I'm creating an application for data visualization.
To keep it simple, I have multiple plots (I'm using QCustomPlot), organized in a VLayout. I put this layout in a QWidget and set this widget as the Central Widget of the main window.

Now, I want to be able to draw a vertical line all over the central widget on the mouse position when I click it. Then I will compute the average of the data that are on this line.

I can't find a way to make it. Do you have any advice ?
I read that I may use QPainter but I can't figure out how it works...