**BUG**
Concise problem statement:
As the image <http://i.imgur.com/PC0GIRH.png> shows it is possible to click on a data point in a WaveForm trace and then accidentally drag it away from the trace.
This is not good for two reasons:
(i) accidentally clickin on a data point on a trace causes the whole trace to highlight because all the data points highlight;
(ii) it is possible to accidentally drag the selected point away from it's correct position.
It is especially easy to accidentally select a data point in a plot of a large dataset when using the click-and-drag cursor movement.
The changes made this way are not permanent: they do not appear in a saved copy and so can not be exported but tis may confuse users.
Is there a way to stop this happening?
Steps to reproduce bug:
1. Run a sim that generates a plot in WaveForm;
2. Click close to the trace until it highlights purple then drag a datapoint away from the trace.
Results:
As shown in the uploaded image.
Expected results:
It should not be possible to edit the traces once plotted.
Url: plot cannot be saved.
Browser: Chrome on WinXP
