2.45 bug with node?

I got few trouble so i describe my work, to see what could be reported, and what are just a limitation.
I ve done a fluid simulation and add a transparent material to it.
I add a material as environnement so as to get good reflexion (angular map).
i do a render and i like it, but i want a ramp in the background and not the reflected map.
At first i did not see the flip xy so i decide to use node.
I add a blend texture in the scene so as to use it in the compositing editor.
I got few trouble .The first : i decide to use the rotate node to rotate the texture. but you can t.You need to convert it into an image by using a mix node. It could be cool to make this node accept color as an image. But with the mix node it works. The next trouble is that it scale the output about 3X. So you need to use a scale node after the rotate node.Once that was done i noticed something; my alpha dont take into account the transparency of the fluid so the ramp don t show throught the fluid if someone know how to do to get an alpha that take transparency into account?

I don’t go anywhere near fluid sims but you more than likely used Ray Trans on the fluid. If that’s the case then plug the fluid layer into the bottom socket of a set alpha node and the other layer into the top then reduce the factor of the set alpha node.