Display values for missing items in combo boxes

include/ui/noscrollcombobox.h

@@ -10,6 +10,7 @@ class NoScrollComboBox : public QComboBox
 public:
     explicit NoScrollComboBox(QWidget *parent = nullptr);
     void wheelEvent(QWheelEvent *event);
+    void setTextItem(const QString &text);
 
 private:
 };

include/ui/tileseteditor.h

@@ -136,6 +136,7 @@ private:
     void copyMetatile(bool cut);
     void pasteMetatile(const Metatile * toPaste);
     bool replaceMetatile(uint16_t metatileId, const Metatile * src);
+    void setComboValue(QComboBox * combo, int value);
 
     Ui::TilesetEditor *ui;
     History<MetatileHistoryItem*> metatileHistory;