While the 'swap hands' function is allocated to the 'g' key, pressing the 'g' key when searching for items in the Creative Mode inventory swaps the items in the player's hands while the items are being searched. This makes it impossible to search for signs without swapping the items in the player's hands.

EDIT: I have more information now. Part of the issue was that I had both the 'place block' and 'swap hands' functions allocated to the 'g' key and then I switched 'place block' to the 'f' key. After doing this, typing the 'g' key when searching for items highlighted the letters I had previously entered into the search bar and then deleted them when I pressed another key. If I leave both functions allocated to the 'g' key, typing 'g' into the search bar swaps the items in my hands.