diff -r e0af4ce7d8bc -r e1ae6d8e84b0 QTfrontend/sdlkeys.cpp
--- a/QTfrontend/sdlkeys.cpp	Wed Jan 09 16:27:57 2019 -0500
+++ b/QTfrontend/sdlkeys.cpp	Wed Jan 09 22:09:27 2019 +0100
@@ -197,3 +197,6 @@
 char controllerleft[128] = QT_TRANSLATE_NOOP("binds (keys)", "Left");
 char controllerright[128] = QT_TRANSLATE_NOOP("binds (keys)", "Right");
 
+//: When a control has no key binding
+char unboundcontrol[128] = QT_TRANSLATE_NOOP("binds (keys)", "(Unused)");
+