function insertImage (img_str, field_id) {
    var oArea = document.getElementById(field_id);
//    var area_value_length = oArea.value.length;
//    oArea.value = oArea.value.substring(0,oArea.selectionStart)+img_str+oArea.value.substring(oArea.selectionStart,area_value_length);

    if (oArea.setSelectionRange) {
        // W3C/Mozilla
        oArea.value = oArea.value.substring(0,oArea.selectionStart) + img_str + oArea.value.substring(oArea.selectionStart,oArea.value.length);
    }
    else if (document.selection && document.selection.createRange) {
        // IE code goes here
        oArea.focus(); //or else text is added to the activating control
        var range = document.selection.createRange();
        range.text = img_str + range.text;
    }
}

function preview_text() {
    var oForm = document.getElementById('texts_form_id');
    oForm.action = oForm.action + '&preview=1';
    oForm.submit();
}