Most obvious when using grayscale images. Not only on dissolve transition, but on any as well. When using composite transition changing alpha channel operation from "Over" to "And" or "Or" makes green tint disappear. The value of the opacity is not important, it could be zero, and as soon the transition reach its end point the green tint is gone. Some image examples:
Normal image:

With dissolve transition

It is annoying, when I just need simple dissolve I have to animate composite transition and change the alpha channel operation. Green tint is not just on project monitor it is there on rendered video too.


Kdenlive, Version 0.9.6 from sunab PPA
Ubuntu Studio 12.04

This is probably this bug http://kdenlive.org/mantis/view.php?id=2759
Which is actually a MLT bug http://sourceforge.net/p/mlt/bugs/198/
Apparently fixed in a recent version of MLT .

But noone has reported into mantis bug tracker if the new MLT version has fixed it

My experience is that it hasn't been properly fixed, albeit this may actually a bug related to luma calculation for different alpha operations. But since I'm unsure, I didn't report to mlt ... I think this still is an mlt issue.

I had the very same issue and it drove me nuts!
When I used Kdenlive generated transparent title clips they caused a green tint while fading and brightned up the whole video as long as they were there.
Forcing a wrong colorspace fixed the brightening up issue but the green tint was still there during fading.

Finally I worked around this by getting simply Kdenlive 0.9.10 (using the ppa:sunab/kdenlive-release repository) and now everything is working without green tints or other color changes.