private void on_entry_time_changed(object o, EventArgs args)
{
if(Util.IsNumber(entry_time_value.Text.ToString(), true)){
entryTime = entry_time_value.Text.ToString();
label_speed_value.Text = Util.TrimDecimals(
Util.GetSpeed (entryDistance, entryTime, metersSecondsPreferred) , pDN);
button_accept.Sensitive = true;
} else {
button_accept.Sensitive = false;
//entry_time_value.Text = "";
//entry_time_value.Text = entryTime;
}
}