Pedro,

you should be able to simply do this in the When

return ! this.Value

or

return ! Table1.Passou

>In a Grid, I have placed a CheckBox with a graphic style
>
>When the user clicks on the CheckBox, a second form is opened to introduce additional data.
>
>The controlSource of this CheckBox is a logical field. In the picture of the CheckBox I have placed
>a red image and at the DownPicture is a green image.
>
>What I need is that once the CheckBox "turns" green, it will/should never again turn red
>and normally this is for each grid entry.
>
>For example, assume I have 10 entries in the Grid, in 2 of them I have already filled in
>the extra fields, therefore the CheckBox appears green, whilst the other 8 are with unfilled fields so
>the CheckBox will be red.
>
>At the red CheckBox I am allowed to click to open a new form, but if I click the green Checkbox, nothing
>should happen and the CheckBox should still maintain green.
>
>I have already tried placing a NODEFAULT at the click and at the interChange, but this still does not work.
>
>The auxiliary data gets stored in Table1.Passou
>Table1.Passou = .T. (Green)
>Table1.Passou = .F. (Red)