The 'Set Metadata' windows does not support the Ctrl+Backspace shortcut, as it treats that combination as a unknown control character (displays a box). I request you fix it so that it act consistent with how Opus handles that control character on its other windows? (For example, on Listers, when renaming, Opus recognizes the control character and does the associated action.)
This request is similar to the ones on the post "Text Fields Inconsistency".