Using keys such as Alt and Ctrl result in characters being typed out

Bug Reports
1

Title:
Using keys such as Alt and Ctrl result in characters being typed out.
Summary:
When typing in a text field, pressing Alt, Ctrl, Shift or Caps Lock types İ, į or IJ characters. In addition, they also have their usual effects, such as Caps Lock switching between uppercase and lowercase characters.
Steps to reproduce:

  1. Start typing in a text field that allows all characters, such as the password field during the registration or player search.
  2. Press Shift, Ctrl, Alt or Caps Lock.

Expected Results:
No characters are typed when pressing these buttons.
Actual Results:
Pressing these keys results in characters being typed, in addition to keys fulfilling their usual role.
Notes:
İ is the only character visible in game out of the 3 mentioned above. į and IJ appear as wide spaces. Using English language in-game.
Attachments:

Game Version:
v1.17545
System Information:
Linux Mint 18.3, Polish keyboard layout.