support for 'reference grabbing'

Hi,

I'm interested in using Sigma grid to let users type expressions into cells, perform the evaluation of those expressions on the server, and display the results in the grid. The important feature that I'm currently not sure how hard it will be to implement is to allow what I call 'reference grabbing' - i.e. for a user in the middle of typing an expression to use cursor keys or mouse drags to specify a cell range that is inserted into the expression at the text cursor, while highlighting the grabbed range on the grid using dotted color borders or marching ants.

I've implemented this from scratch already for two different desktop GUI grid components, and am now looking at trying it on a web-based grid. I have not been able to find mention of explicit support for this in the Sigma grid documentation or samples, so I'm assuming I'll have to code this behaviour from scratch again. Are there any reasons to think Sigma grid will make this easier (or harder) than its other web-based competitors?

Many thanks for any pointers or suggestions anyone has.

Jonathan