Bug in confocal optimizer

[alrik-durand]

What is affected by this bug?

Master.

When does this occur?

In confocal GUI, an optimize call displays a "Stop" button for the scan, as it should.
When the color bar scale is changed, this stop button disappear like if the optimized was finished, while it's not.

Expected behavior (i.e. solution)

If a scan or optimize is ongoing, a stop button should be available.