App Crash when opening Volumen Slider an Combo-Box at once

[Thomas Roskop]

When Kazam Preferences Windows is open an you go to the General-Tab you can see to volume-Icons. Clicking on one of them pops out an vertical slider where to change the volume.
When the slider is open and you than select either Speakers or Microphone-Combobox (the Drop-Down-Icon), than this Window will hang for a few seconds until the app crahes.

This error is not easy to reproduce because you need to be very fast.
But i also found an other similar error. When you doppel click the Volume-Button very fast or very often, than the App will crash.