When you stop the drag and release the button (or life your finger), the stability parameters will be shown.
Note: If the temperature and dew point overlap, start your drag a little to the left to change the dew point, or a little to the right to adjust the temperature. Remember, the dew point value cannot be higher than the temperature!
The purple line that appears after you change a temperature or dew point shows the temperature that a "parcel of air" lifted from the surface would have. The single square on this line is the Lifting Condensation Level where the air would become saturated and a cloud might form.