[Bug]Posteffects cause stretching

Hi,

we just experienced some strange behavior from one of our older applications, after some testing and trying we were able to find the cause of it:
If a post effect is applied onto the camera and the project is set to Fill Mode: Fill Window the application does not resize correctly anymore.

Please find screenshots and reproduction steps in the dev log of the project.
I already invited @vaios to the project, I hope that was okay :blush:

>>TO PROJECT

Sounds like this is the same issue as here: https://github.com/playcanvas/engine/issues/474

A bit delayed over the holidays, but this should be fixed very soon.