Hi, I need to display a checkbox component with 4 choices but 2 not selectable b

Could you create 2 checkbox components (one with 4 choices, the other with 2 choices) that save to the same variables? You would then show/hide them based on pv!selectable.

No, my point is to show in one checkbox 4 choice but allow users to choose only between 2.

You could create 2 checkbox components (one 'A' with always selectable with 2 choices and other 'B' with remaining). Now Change B's select ability according to your condition.

Yes, but it puts a space between the 2 checkboxes which is ugly...isn't there some JavaScript to help me do that?

In my forms I accomplish this by running an onClick() JavaScript function that checks which values are selected against which can be selected (using a hidden field on the form - hidden by JS onLoad(), to keep track of allowable fields). The JS function can then alert the user when they select a blocked field, and then remove the selection. This does not grey out the fields that are unallowable, but they get the idea pretty quick. This also works great for requirements such as "show 10, allow up to 3 choices".