Limit the number of selections in a list box(or drop down)

[#1]

Hi,

Can you please help solve the below problem of limiting the allowed number of selections in a list box or drop down

Lets say I have a list box with 4 possible value (the values may have white space or special characters)

A

B

C

D

I would like to restrict the user the ability to select not more than 2 values at a time. Either selection of a third value should be disabled or even when selected should be ignored or when the third value is selected the first values should be automatically de-selected.

Thanks

[Anonymous]

How about putting on a Document level OnSelect Trigger on the field, that clears the selections if the count of that field is greater than 2.

[#3]

Hi Bill,

Thanks for a quick response. Can you please explain with an example? I cannot get the expression right to clear the selection when a third value is selected.

Thanks