Text editor: incorrect / unexpected behavior of Ctrl-Shift-Left/Right w.r.t. (word) selection

[Jan Vrany]

Copied from comment #124, ​comment 16

Steps to reproduce:

1. Open an empty workspace and type three words as in:

   AAA BBB CCC
   

2. Position cursor in the middle of word BBB and do select word (press Alt-w). Word BBB should be selected afterwards.
3. Try to extend the selection word-wise to the left by pressing Ctrl-Shift-Left

Observed behavior

I have tried this patch, part works part not.
The part that works is pressing the alt+w (ad 2) ). That correctly select a word.
The part that does not work, in my opinion, is ad 3). There if you press ctrl+shift+left it deselects the BBB part of the text and in subsequent press it select first the space between AAA BBB and then it select also AAA, but the BBB is deselected.

I have also tested a combination ctrl+shift+right which partially works. It correctly selects space between BBB CCC, however, when I try to select with one more ctrl+shift+right keypress also CCC, when I have 10 empty lines it selects CCC, but also the all the 10 lines below it, probably till the EOF. The correct behavior, in my eyes, would be just to select CCC till the EOL instead of EOF.