private void on_entry_distance_changed(object o, EventArgs args)
{
if(Util.IsNumber(entry_distance_value.Text.ToString(), distanceCanBeDecimal)){
entryDistance = entry_distance_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_distance_value.Text = "";
//entry_distance_value.Text = entryDistance;
}
}