You can lock the style or the filter node you are working on and move to another filter in the Style Editor to change its parameters and immediately see the preview, without the need to switch between the two filters' Properties + Preview panes. First, create a project with a few filters and styles added to the image in the Style Editor as shown in tutorial: 3.4 Creating a Style in the Style Editor: Complex Styles 

 

_____Lock the Preview

We will be modifying the curve as we want to see its effect immediately applied to the Tone Mapping filter. Chose the preview you want to keep visible: Tone Mapping by selecting the filter and clicking the Lock icon in the Properties+Preview pane. 

Select the filter node in the graph that you want to change, in our example: Circular Curve, and change its properties in the Properties + Preview pane. The preview we have locked previously will now be rendered in real time. If we haven't locked the Tone Mapping filter, we would be seing the Curve's preview and we would have had to click the Tone Mapping filter to see how the changes afflicted the image. By using the lock, we do not have to go back and forth between the filters. 

We now want to modify the Outlines so to see the result we will lock the whole preview, which corresponds to Layer #1. Unlock the previous Tone Mapping filter, and click Layer#1. Lock it by clicking the small lock icon in the Properties + Preview pane.

Select the filter node in the graph that you want to change: Outlines with Scanned Brushes and change its properties. The preview we have locked previously will now be rendered in real time and a Progress Bar will show the elapsed processing time.

Do some other modifications at the filter to see the effects. We have changed the Detector type, the Brush family, and changed the Minimal and Maximal stroke lengths too by dragging the sliders to what we considered the best result. 

Our result is visibile immediately in the Preview pane. 

When you are done, unlock the filter. Our final image is: 

You can download the project zip file containing the PWS Project and the image from : here