It appears that the function popup menu in Drosera calculates its location and size for hit testing based on the location and size of the currently selected value in the menu, rather than the size of the control in the user interface. This can lead to very small and non-obvious click areas for small function names.
This appears to be the case for the files popup menu as well, although it's significantly less obvious.
Created attachment 11374 [details]
Slightly cheesy fix
Created attachment 11375 [details]
Better value choice (matches the control rather than being bigger, now)
Landed in r17601.
Closing since Drosera has been replaced by the new Web Inspector debugger. Moving to the New Bugs component so the Drosera component can be closed and removed.