From the title screen, pressing Tab twice and Space once opens the "Singleplayer" screen while also filling the search box with a space. For some reason, the space key is getting consumed by the game twice. It's also possible this is happening with the enter and keypad enter keycodes but is not noticeable as they do not change the search box.

This bug does not seem to affect other screens where a text box is the first focused widget. For example, Tabbing to the "Edit" button under a world in the "Singleplayer" screen and pressing Space does not add a space to the "World Name" textbox like on the "Singleplayer" screen.