private void on_entry_tc_value_changed(object o, EventArgs args)
{
if(Util.IsNumber(entry_tc_value.Text.ToString(), true)){
entryTc = entry_tc_value.Text.ToString();
button_accept.Sensitive = true;
} else {
button_accept.Sensitive = false;
//entry_tc_value.Text = "";
//entry_tc_value.Text = entryTc;
}
}