I would also like to see a "pick by comparison" condition added. For now just use a instance variable.
So the CC event:
+Sprite: pick by comparison distance(Sprite.X, Sprite.Y, MouseX, MouseY) Less Than 100
--- do something
Is done in C2 like so:
+Every tick
--- Sprite: set dist to distance(Sprite.X, Sprite.Y, Mouse.X, Mouse.Y)
+Sprite: dist < 100
--- do something