Cancel button is missing in "Insert picture" pop-up window

The Cancel button is missing in "Insert picture" pop-up window.

Steps to reproduce (A):
1) Open and login Jcommune in any browser.
2) Click "New topic" button in any branch.
3) Click “Insert picture” BB-Code button.

Actual result: The modal window “Enter Image URL” is demonstrated. The Cancel button is absent in this window.
Expected result: There is "OK" and "Cancel" buttons.

Steps to reproduce (B):
1) Open and login Jcommune in any browser.
2) Go to any topic and click “Answer” button.
3) Click “Insert picture” BB-Code button.

Actual result: The modal window “Enter Image URL” is demonstrated. The Cancel button is absent in this window.
Expected result: There is "OK" and "Cancel" buttons.

Steps to reproduce (C):
1) Open and login Jcommune in any browser.
2) Click “Messages” button at the top right.
3) Click “Insert picture” BB-Code button.

Actual result: The modal window “Enter Image URL” is demonstrated. The Cancel button is absent in this window.
Expected result: There is "OK" and "Cancel" buttons.

Note: This bug was found in TC JC558 (#24).