try (destroydialog X ) catch ()
rollout X "" (

    CheckButton showIndexes "Show face indexes"
    
    fn ShowTriIndexes =
    (
        gw.setTransform (matrix3 1)
        
        for s in selection where canConvertTo s Editable_mesh do
        (
            local tmp = snapshotAsMesh s
            
            for f=1 to tmp.numfaces do
            (
                local fv = getFace tmp f
                local c = ((GetVert tmp fv[1]) + (GetVert tmp fv[2]) + (GetVert tmp fv[3])) / 3.0
                
                gw.text c (f as string) color:yellow
                
            )
            
            free tmp
            
        )

    )


    on showIndexes changed state do
    (
        if state then registerRedrawViewsCallback ShowTriIndexes else unregisterRedrawViewsCallback ShowTriIndexes
        redrawViews()            
    )
    
    on X close do unregisterRedrawViewsCallback ShowTriIndexes

)
createDialog X pos:[100,100]