DPS capped by mana regen

Is your feature request related to a problem? Please describe.
I'm toying with a build which has cast rate of 4.26, doing 810k DPS. Main skill's mana cost is 104. Cast rate is 4.26. But what if I have only 105 mana and my mana regen is 121.8? Such mana pool cannot allow for such cast speed, so the skill is mana-starved, so the DPS should be displayed as much lower. Also tooltips over mana regen / mana size doesn't show impact on dps in such scenario.

Describe the solution you'd like

• calculate "available mana per second" (mps_a) and "required mana per second" (mps_r) for a given skill
• check if they mps_r < mps_a, if not, notify that build is mana-starved
• preferably display estimated mana-starved DPS (dps_base * min(1.0, mps_a / mps_r)), perhaps in red color?

Describe alternatives you've considered

• the other solution would be just showing mps_r for each skill and mps_a in tree view and/or calculations tab.

The issue provides no file or test entry point. Start by tracing where per-skill DPS, cast rate, mana cost, and regeneration are calculated; then verify the displayed DPS and mana-related tooltips against the reported example and the requested mana-starved behavior.