Crystal REVS is the best context-sensitive editor there is. Has Flowcharts, Call/Caller Trees, Tokens/Comment Panel, Auto-Format, Visio export, State diagrams.
Editions:
Rules: MISRA C Static Checking
DataFlow: Rich Trees, Object DataFlows, CallFlows, Inline expansion of flowcharts
Docs: Flowcharts/Trees in HTML docs
Professional: Publisher, Custom symbols, Batch output Flowcharts/Trees
ProPlus: All features + Full Project Flowchart