I've managed to hack it into layout.js by setting this.runtime.linearSampling to this.runtime.pointSampling in the Layout.prototype.draw and Layout.prototype.drawGL functions. Then if I use low-quality fullscreen scaling I get point sampling for the displayed gfx. It's not ideal. You need to re-apply the changes in layout.js every time there's an update and Scirra don't like us messing with official plugins due to possible compatibility issues with our capx files. It's a purely cosmetic change tho so shouldn't be a problem far as I can tell.