May be you known the Eclipse Editor, or the IDA Disassembler Tool. They are a nice feature. When you click on a symbol, all the occurrences of this symbol are highlighted (like "Find Symbol" but in real time). And the occurrences are shown in the scroll bar.
We assume you know about our Find References command, to which you can assign a shortcut. We also recommend you enable "highlight references" in our options dialog. You'll get close to what you want.
In fact, it's a feature you need to try to 'feel' his power. Specialy when you read an old source code, or the source code of someone else. You understand very very quickly the code like this.
Press a shortcut is not an acceptable option because this feature need to be a 'passive' action to be useful, not an active one.