How to make a full screen window

[ovidiucucu]

If you want full-screen functionality as implemented in most applications, that's it: in full screen-view you have to remove caption as well as the menu bar.
Here is a brief example how to toggle between normal and full-screen view:

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
   int wmId, wmEvent;
   // ...
   switch (message)
   {
   case WM_COMMAND:
      wmId = LOWORD(wParam);
      wmEvent = HIWORD(wParam);
      // Parse the menu selections:
      switch (wmId)
      {
      case ID_VIEW_FULLSCREEN: // toggle full screen
         if(g_bFullScreen)
            _ViewNormal(hWnd); 
         else
            _ViewFullScreen(hWnd);
         break;
         //...
      //...
   //...

void _ViewFullScreen(HWND hWnd)
{
   // keep in mind normal window rectangle
   ::GetWindowRect(hWnd, &g_rcNormal);

   // remove caption and border styles
   DWORD dwOldStyle = ::GetWindowLong(hWnd, GWL_STYLE);
   DWORD dwNewStyle = dwOldStyle & ~(WS_CAPTION | WS_THICKFRAME);
   ::SetWindowLong(hWnd, GWL_STYLE, dwNewStyle);

   // remove the menu bar
   ::SetMenu(hWnd, NULL);

   // resize to full screen view
   // NOTE: use SWP_FRAMECHANGED to force redraw non-client
   const int x = 0;
   const int y = 0;
   const int cx = ::GetSystemMetrics(SM_CXSCREEN);
   const int cy = ::GetSystemMetrics(SM_CYSCREEN); 
   ::SetWindowPos(hWnd, HWND_TOPMOST, x, y, cx, cy, SWP_FRAMECHANGED);

   // set full screen indicator
   g_bFullScreen = TRUE;
}

void _ViewNormal(HWND hWnd)
{
   // put caption and border styles back
   DWORD dwOldStyle = ::GetWindowLong(hWnd, GWL_STYLE);
   DWORD dwNewStyle = dwOldStyle | WS_CAPTION | WS_THICKFRAME;
   ::SetWindowLong(hWnd, GWL_STYLE, dwNewStyle);

   // put back the menu bar
   ::SetMenu(hWnd, g_hMenu);

   // resize to normal view
   // NOTE: use SWP_FRAMECHANGED to force redraw non-client
   const int x = g_rcNormal.left;
   const int y = g_rcNormal.top;
   const int cx = g_rcNormal.right - g_rcNormal.left;
   const int cy = g_rcNormal.bottom - g_rcNormal.top; 
   ::SetWindowPos(hWnd, HWND_NOTOPMOST, x, y, cx, cy, SWP_FRAMECHANGED);

   // reset full screen indicator
   g_bFullScreen = FALSE;
}

Further, to keep some functionality provided by the menu or the title bar buttons when in full-screen view mode, you can use accelerators and/or context menus.

I have attached here a simple demo application.