Rename file within a track

[Thangalin]

Feature request: The ability to point an image in a track to a different file.

Usage scenario: Imagine creating a set of videos where the introduction is, for the most part, the same. The introduction, however, changes ever-so-slightly from one video in the set to the next. (For example, one video might animate the word "Basic" while another video animates the word "Intermediate" -- the rest of the introduction, animations, fades, etc., would remain the same.)

It would be easier if you could create the new file (e.g., "intermediate.png") and simply redirect the elements in the existing track to use the new file.

In my case, I have six different uses of the word "basic" but want the animation to remain the same for all six cases (slide in from left, slide out to right, fade in, fade out, etc.) regardless of the word ("basic", "intermediate", "advanced", etc.). This means that I have to remove the "basic.png" six times, then carefully align and configure "intermediate.png" six times to replace "basic.png".