Inconsistent functioning entering buttons

[Suprnova]

The program will not work as intended if you enter your keys by pressing the key you want in the dialog box as opposed to just pressing the key you want immediately.
Gif Demonstration
Pressing a key without selecting the dialog box will work, and will have an uppercase label, but pressing a key when selecting a dialog box will not work, and will have a lowercase label. If you first press a key without selecting the dialog box and then try to type it in the dialog box, it will work and you'll have a lowercase label.