Color indication when an engine is starved of fuel

[Kasuha]

I have not noticed it in previous versions, but in 0.23, maybe thanks to better efficiency in resource using, it may happen that an engine is still running when its fuel indicator is already (or at least looks) empty. See image below.

I must say I already staged prematurely several times due to that because in complex designs there's not always good view at flames coming out of engines.

As long as the indicator shows liquid fuel amount, it may also happen that the engine won't run even though there is still liquid fuel available - simply because there's not enough oxidizer available.

Therefore I suggest to add color coding to engines, similar to how parachutes are color coded. Two colors would be enough - white, meaning normal conditions, and red, meaning zero thrust because of lack of required resource.

[Saberus]

I second this, simple and intuitive.

I might also suggest that the bar show which fuel source is lacking, be it LiquidFuel, Oxidizer, IntakeAir, ElectricCharge, or XenonGas (Or Kethane if you use the mod.)