At the moment, you can use the left and right mouse buttons to select two elements at the same time, but how about switching 'sample elements' to a key (e.g. 'e'); and use the middle mouse button for selecting elements as well.
Who hasn't wanted to be able to do that? it makes things a lot easier (when i say a lot, i mean a LOT)
@The-Con you use caps lock, which only selects 'erase particles'. i want to be able to select for example: wood, fire and water this would be useful for filling in time by drawing houses, setting them on fire and putting them out.
@cracker64 thanks, it makes sense now. @azza2 I don't know about changing the middle button, but key bindings would be good. I often find myself having to use a lot of a two specific elements, but having to go through the lists continuously.