make it able to map the Tab key

src/NDSCart.cpp

@@ -903,6 +903,7 @@ bool LoadROM(const char* path, const char* sram, bool direct)
 {
     // TODO: streaming mode? for really big ROMs or systems with limited RAM
     // for now we're lazy
+    // also TODO: validate what we're loading!!
 
     FILE* f = Platform::OpenFile(path, "rb");
     if (!f)

src/frontend/qt_sdl/InputConfigDialog.h

@@ -80,6 +80,8 @@ protected:
     void keyPressEvent(QKeyEvent* event) override;
     void focusOutEvent(QFocusEvent* event) override;
 
+    bool focusNextPrevChild(bool next) override { return false; }
+
 private slots:
     void onClick();
 
@@ -103,6 +105,8 @@ protected:
     void focusOutEvent(QFocusEvent* event) override;
     void timerEvent(QTimerEvent* event) override;
 
+    bool focusNextPrevChild(bool next) override { return false; }
+
 private slots:
     void onClick();