It would be super handy if you could do a quick eyedropper while holding down the Pencil, Paint Bucklet, Line or Rectangle Tool key.
I’m not sure if I understood this feature correctly 
Right now you can use the eyedropper pressing Alt key + left or right mouse buttons from any other tool.
Cierto, pero cuando tienes la goma seleccionada y luego presionas alt para activar el quick eyedropper, y en seguida tratas de dibujar, te das cuenta que no puedes hacerlo porque olvidaste que tenías seleccionada la goma. Si pudiera contar con una tecla que al mantener presionada pudiera activar el quick eyedroper, y al soltar la tecla se activara el lapiz creo que sería mucho más intuitivo.
So after using the Eyedropper the Pencil should be selected automatically? I guess that in the case of paint bucket/lines etc. that tool should be kept instead
It’s a little tricky. Sometimes using the Eyedropper is useful with the Eraser when we use the right-click (right-click will replace the Foreground color with the Background color). Or the Eraser in the Background Layer will use the Background color to erase.
True. I think a more reliable way to do what I say is to use combined keyboard shortcuts. As far as I can see in Aseprite you can assign more than one Tool to a single key. The problem is that you cannot assign two Tools to a single key, if one of them is a (quick) Tool. So the feature that solves my problem would be the ability to freely assign both a quick tool and a normal tool on a single key.