fixes https://github.com/spesmilo/electrum/issues/8853
This is a bit ugly, but activeFocus is declared as final and cannot be overridden directly...
```
1.42 | W | gui.qml.qeapp | file:///home/user/wspace/electrum/electrum/gui/qml/components/controls/ElTextArea.qml:23:5: Cannot override FINAL property
```