RStudio's "packages [x,y,z] required but not installed" prompt is lovely. One small tweak - could it be made to refresh/recheck when script tabs are re-focused? It seems these checks are all performed at startup, so if one fires up RStudio with (e.g.) the same script loaded 5 times, the prompt will suggest users install those same packages 5 times, i.e. it doesn't check to see whether they're already installed.