That's on the wish list. Add your suggestion by clicking on the caret at the top-right of the VP window. 
Real-time is available in Wavepad. Save the edited file and import it back into Videopad.
Alternatively, if the clip in Videopad has audio and video linked, right-click the audio track and Edit In Wavepad.
When done, click the top-right red X to save and close. VP will reappear with the file added to the audio track.
Then UNlink the original clip, delete its audio and slide the video over the newly edited audio track.