i need check mark appearance with a simple click on page

dear sir,

i want check mark appearance with a simple clicking on page, i have
try CheckMarkAppearance function, it works when clicking mouse on
document but a green line box is appear with cursor also..

here is the code

private sub mouse_click()
            Dim emp_last_check1 As Field =
doc.FieldCreate("employee.name.check" & chk, _
             Field.Type.e_check, doc.CreateIndirectName("Yes"))
            Dim sdfdoc As SDFDoc = doc.GetSDFDoc()
            Dim annot3 As pdftron.PDF.Annots.Widget =
pdftron.PDF.Annots.Widget.Create(sdfdoc, New Rect(_start_pt.X,
_start_pt.Y, _start_pt.X + 15, _start_pt.Y + 15), emp_last_check1)
Annot.AnnotationState.e_normal, "Yes")
end sub

Function CreateCheckmarkAppearance(ByRef doc As PDFDoc) As Obj
        Dim builder As ElementBuilder = New ElementBuilder
        Dim writer As ElementWriter = New ElementWriter
        Dim checkmark As Element = builder.CreateTextRun("4",
pdftron.PDF.Font.StandardType1Font.e_zapf_dingbats), 1)
        Dim GState As GState = checkmark.GetGState()
        GState.SetFillColor(New ColorPt(selcolor, selcolor1,
selcolor2)) ' cyan


        Dim stm As Obj = writer.End()

        stm.PutRect("BBox", 0, 0, 1, 1)
        stm.PutName("Subtype", "Form")
        Return stm
    End Function

I am not sure that I understand the question. Could you please send a
sample file or provide more info about the issue? Thank you.