Hi--

I'd like to create a dynamic dropdown in which the contents of the dropdown
(source) is all the values (unique) in the column where the dropdown
operates. If the user enters a new value, one that isn't yet in the column,
I'd like that value to be added to the dropdown next time. So, let's say that
all the cells from B1 to B50 would have a dropdown. Initially, before any
values are entered into that range, the dropdown would be empty. Then, let's
say the user enters "Hello" into B1. When they go to B2, the dropdown would
contain one option: Hello. Now they can either select Hello from the dropdown
in B2 or they can type in another value, let's say, "World". Let's say they
enter "World". Now when they go to B3, the dropdown will have Hello and World
listed. And so on...

Also, let's say the user enters "World" from the dropdown into cell B3. Now
B1 is Hello, and B2 and B3 are World. The dropdowns in the range would not
list World twice!

Is there a way to do this directly in the spreadsheet without using forms?

Thanks!