how to do simple composite add?

[FredThompson]

I've got 2 320x240 ntsc clips. One is longer than the other.

I'd like to create a single 640x240 clip which is both of the source clips, side by side. The last frame of the shorter clip should be persistent for the duration of the longer clip.

How can this be done with AviSynth?

[gzarkadas]

This will do the job:

StackHorizontal(clip1, clip2)

[FredThompson]

danke