On the challenge issuing screen, accessed through Battles -> Defending Sirius -> Challenge! , the input for the text field does not block or catch input properly.
The keyboard shortcuts for the fleet layout screen below still work (I tried shift-F, which got me a Formation order dialog, as well as a capital F), and you cannot enter ! or ?, both of which are essential for good smacktalk.
Finally, the window doesn’t go away after you submit, and lets you submit twice with exactly the same variables. If possible, the button should be disabled after pressing it once, unless the submission failed.