crash in TextInput

[igagis]

1. Run tests/app
2. Click on the text_input
3. Clear all text from it, e.g. using backspace
4. Press and hold the 'M' key
5. While pressing the 'M' key press and hold also the SHIFT key
6. Wait until input cursor reaches right border of the input field

Result: crash due to uncaught exception:

terminate called after throwing an instance of 'std::out_of_range'
  what():  basic_string::substr: __pos (which is 18446744073709551613) > this->size() (which is 25)
Aborted