Turning capturing on and off is probably the single most-used option, and as such is shown in the context menu for the shell notification icon (the only other menu items are: Restore [the window] and Exit).
I leave Fiddler open all day (but not usually capturing), minimising it or hiding it behind other windows as I work.
So it would really useful if the icon changed to indicate whether capturing was enabled or not.
This should be pretty simple.