Fixed in Vuo version:
Steps causing the bug to occur:
Made a composition that auto launches fullscreen and shows the mouse x coordinates as a text layer.
B - Make a checkerboard that matches the screen values and load it in a scaled layer of width 2. Render, on the left side of the window composition, there seem to be a line showing a missing pixel width. On clear wallpapers it isn't obvious as the line is clear itself, but it gets visible on darker wallpapers.
May this be linked somehow with Big Pixel Image Bugs ?
See screenshots on https://vuo.org/node/1305