My wish list item would be the ability to print a cross reference of where "define", "variable" and "function" are declared and used.
The cross reference should search all IDE tabs, and if desired show the line number for each declaration and use location.
Industrial PLC IDE's have this feature and it is very very useful.
Granted for 'small' programs it might not be needed, but as programs grow it becomes a very useful tool.
I am writing an Arduino program right now of greater than 20 pages of code and I am wishing I had this feature right now !