45.beta.1
=========
* Fix input handling in alt-tab and several other components [Carlos; !2872]
* Fix screenshot tool [Florian; 2877]
* Export notification source classes for extensions [Andy; 2869]
* Finishing ESM porting touches [Florian; 2880]
* Misc. bug fixes and cleanups [Andrew, Carlos, Florian; !2866, !2871,
  !2876, !2878, !2879]

Contributors:
  Carlos Garnacho, Florian Müllner, Andy Holmes, Andrew Zaech

Translators:
  Piotr Drąg [pl], Kukuh Syafaat [id]