Keys to select or delete a word doesn't work
For some reason for editing text in textbox it is only possible to delete or select just a single character at a time. Common key combinations, like Ctrl+Backspace or Ctrl+Shift+Left, are work like if modifier keys ignored.
Steps to reproduce:
1. Start GeoGebra Classic 6
2. Click the textbox for typing formulas as in illustration.
3. Type "test", then press either Ctrl+Backspace to delete the word, or Ctrl+Shift+Left to select it.
Expected: The word deleted or selected.
Actual: only single character deleted or selected.
Version: 6.0.414.0-offline (December 2017)
Systems tested: Archlinux and Ubuntu 16.04 Xenial.