Disable progressive preview on cached tweaks

I suggest an option for automatic disabled progressive preview when tweaking "optimized" parameters.

Example: In FF2 when changing black, mid and white point in ambient occlusion *after* first full rendering, you don't have to wait for a complete re-rendering, since internal buffering makes it work almost real time. But in FF3 you have to wait for the progressive passes before you get a detailed rendering, which is not very useful. The same applies to several other shader parameters.

FF could check if the tweaked parameter only uses buffered data, and then not use progressive preview.

- "Then just disable the progressive preview" - Well, no, because it is indeed a nice feature for the first "original" (i.e. unbuffered) rendering.

While I'm at it: in general I miss direct main menu control of preview modes (now you have to navigate it into the prefs..). The view menu could contain a sub menu called "Preview mode" with the options: "Full", "Two pass", "Progressive". Full being a "new" mode where anti-alias is rendered after each tile instead of after all tiles. "Two pass" is the normal ("old") mode. "Progressive" is well... progressive.
Each should have a short cut, say ctrl+1, ctrl+2, ctrl+3.