I've had a similar task previously. Since lines aren't accessible with conditional formatting, I ended up having the duplicated behind the checkbox field, set as an edit field (no browse/find), then set the conditional formatting on that field. This might not give you exactly what you want, but I think with layering a second field, you might get the effect you'd like. Good luck!
Definately what i have working so far is an addRemoveItem from list. Simple calcuation which i found a custom function for.
Conditional formatting is doing a patterncount and then highlighting based on the patterncount.
this is way harder than it needs to be - I must be learning something here.
There are several ways to do this, but the easiest way to do it is to:
1. create a button
2. Right click on the button and add the conditional formatting formula "not IsEmpty( PortalTable::thePortalCheckboxField )" and set the fill color to whatever color you want the highlight to be
3. Resize the button to be the same size as your first portal row
4. Move into the portal row and move it behind all of the existing fields in the portal
5. Remove it's effect (take off the emboss), it's line (set line size to 0), and remove it's fill color. At this point it will be a clear object
6. Go into browse mode and check it out
In the end, what you get is an invisible object that gets a different background color when the checkbox for that portal row has a value in it. the advantage of using a button instead of a field is that you're not having to create a field in your table just for a highlight and if the button doesn't have an action attached to it, there's not really a difference between a button and a rectangle object. You just have to make sure that the formula for the conditional format uses the checkbox that is located in the table that the portal is pointing to, that's how FM can tell that you're highlighting just one portal row vs all portal rows.
Oh, you didn't beat me to it, I forgot you were the one that originally asked the question
Anyway, I like to highlight the entire row instead of just the check box, but really you can do the same thing to the checkbox field.