Call DefWindowProc when WM_KEYDOWN, WM_SYSKEYDOWN are not handled

src/core/hle/D3D8/Direct3D9/Direct3D9.cpp

@@ -1619,6 +1619,10 @@ static LRESULT WINAPI EmuMsgProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lPar
             {
                 ToggleFauxFullscreen(hWnd);
             }
+            else
+            {
+                return DefWindowProc(hWnd, msg, wParam, lParam);
+            }
         }
         break;
 
@@ -1655,6 +1659,10 @@ static LRESULT WINAPI EmuMsgProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lPar
                 if(g_iWireframe++ == 2)
                     g_iWireframe = 0;
             }
+            else
+            {
+                return DefWindowProc(hWnd, msg, wParam, lParam);
+            }
         }
         break;
 

src/gui/WndMain.cpp

@@ -381,6 +381,10 @@ LRESULT CALLBACK WndMain::WndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lP
             {
                 SendMessage(m_hwndChild, uMsg, wParam, lParam);
             }
+            else
+            {
+				return DefWindowProc(hwnd, uMsg, wParam, lParam);
+            }
         };
         break; // added per PVS suggestion.
 
@@ -514,6 +518,10 @@ LRESULT CALLBACK WndMain::WndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lP
                     {
                         SendMessage(m_hwndChild, uMsg, wParam, lParam);
                     }
+                    else
+                    {
+                        DefWindowProc(hwnd, uMsg, wParam, lParam);
+                    }
                 }
             }
         }