Suggestions:

• Inline Shortcutbutton into Listview
• Put the loadable schemes in a combo box
• Elide names in the middle
• Warn about duplicate shortcuts
• Offer "insert backspace", "tab", "shift-tab" buttons, and don't put these keystrokes in directly, so tabbing still works, and backspace can delete the current shortcut
• Offer a way to set a shortcut by "shortcut string" (similar to QKeySequence(QString) constructor), as a workaround for all the situations where detecting the right key combination fails