How can I switch between custom preview panel and default preview pane in windows file explorer?

Question

I created my custom preview for "*.txt" files via using SharpShell. For creating preview pane I used the example from next link:

https://github.com/dwmkerr/sharpshell/tree/master/SharpShell/Samples/PreviewHandler

My custom preview pane works well but in some specific case I need to display the default preview. How can I do it?