   GL_INVALID_OP in fullscreen mode only
  I've had a simple game working fine, and have had no problems until I decided to switch it over to fullscreen mode. Unfortunately once I enable fullscreen mode I am starting to receive GL_INVALID_OPERATION errors every time I check glGetError. This doesn't happen in windowed mode, and I'm trying to understand what might be causing this to happen. The window goes into fullscreen mode just fine, and actually partially works, all of my fullscreen background quads are rendered and some of my background shaders are executing properly, but none of my meshes are appearing. So I know that OpenGL is functioning to some extent.Anyway that is all anecdotal, just really trying to figure out why I'm getting these errors. I'll paste my startup code and see if anyone notices anything.int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd){WNDCLASSEX windowClass;// window classHWND   hwnd;// window handleMSG   msg;// messageRECT   windowRect;windowRect.left=(long)0;// Set Left Value To 0windowRect.right=(long)WINDOWWIDTH;// Set Right Value To Requested WidthwindowRect.top=(long)0;// Set Top Value To 0windowRect.bottom=(long)WINDOWHEIGHT;// Set Bottom Value To Requested Height// fill out the window class structurewindowClass.cbSize= sizeof(WNDCLASSEX);windowClass.style= CS_HREDRAW | CS_VREDRAW | CS_OWNDC;windowClass.lpfnWndProc= MainWindowProc;windowClass.cbClsExtra= 0;windowClass.cbWndExtra= 0;windowClass.hInstance= hInstance;windowClass.hIcon= LoadIcon(NULL, IDI_APPLICATION);// default iconwindowClass.hCursor= LoadCursor(NULL, IDC_ARROW);// default arrowwindowClass.hbrBackground= NULL;// don't need backgroundwindowClass.lpszMenuName= NULL;// no menuwindowClass.lpszClassName= "GLClass";windowClass.hIconSm= LoadIcon(NULL, IDI_WINLOGO);// windows logo small iconif (!RegisterClassEx(&windowClass)){DWORD err = GetLastError();return 0;}CreateGLWindow(windowClass,windowRect,hInstance,&hwnd);...Looking good so far...bool CreateGLWindow(WNDCLASSEX windowClass, RECT windowRect, HINSTANCE hInstance, HWND *hwnd){DWORD   dwExStyle;// Window Extended StyleDWORD   dwStyle;// Window StyleHGLRC hRC;if (fullscreen)// fullscreen?{int monitors = GetSystemMetrics(SM_CMONITORS);DISPLAY_DEVICE dd;DEVMODE dm;dd.cb= sizeof(dd);std::vector<DISPLAY_DEVICE> devices;std::vector<DEVMODE> devmodes;int i = 0;while(EnumDisplayDevices(0,i,&dd,0)){devices.push_back(dd);EnumDisplaySettings(dd.DeviceName,ENUM_CURRENT_SETTINGS,&dm);devmodes.push_back(dm);i++;}DEVMODE dmScreenSettings;// device modememset(&dmScreenSettings,0,sizeof(dmScreenSettings));dmScreenSettings.dmSize = sizeof(dmScreenSettings);dmScreenSettings.dmPelsWidth = devmodes[1].dmPelsWidth;// screen widthdmScreenSettings.dmPelsHeight = devmodes[1].dmPelsHeight;// screen heightdmScreenSettings.dmBitsPerPel = devmodes[1].dmBitsPerPel;// bits per pixeldmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;if (ChangeDisplaySettingsEx(devices[1].DeviceName,&dmScreenSettings,0, CDS_FULLSCREEN,0) != DISP_CHANGE_SUCCESSFUL){MessageBox(NULL, "Display mode failed", NULL, MB_OK);fullscreen = FALSE;}}if (fullscreen)// Are We Still In Fullscreen Mode?{dwExStyle=WS_EX_APPWINDOW;// Window Extended StyledwStyle=WS_POPUP;// Windows StyleShowCursor(FALSE);// Hide Mouse Pointer}else{dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;// Window Extended StyledwStyle=WS_OVERLAPPEDWINDOW;// Windows Style}AdjustWindowRectEx(&windowRect, dwStyle, FALSE, dwExStyle);// Adjust Window To True Requested Size*hwnd = CreateWindowEx(NULL,// extended style"GLClass",// class name16829936"Isle",// app namedwStyle | WS_CLIPCHILDREN |WS_CLIPSIBLINGS,0, 0,// x,y coordinatewindowRect.right - windowRect.left,windowRect.bottom - windowRect.top, // width, heightNULL,// handle to parentNULL,// handle to menuhInstance,// application instanceNULL);// no extra paramsThis section is the only difference I have between fullscreen and windowed mode, just changing some Display Settings. I'm not real experienced here so its possible I'm doing something stupid. Calling CreateWindowEx fires off a CALLBACK MainWindowProc with message WM_SIZE, where I'm checking for opengl error. In windowed mode this passes just fine, while failing with GL_INVALID_OPERATION in fullscreen.Any ideas?   
  I don't understand this:devices[1]...Anyway, could you post the actual change code? If it's just a ChangeDisplaySettingsEx, then I think you need a AdjustWindowRectEx too.What happens if you start with fullscreen initially? (not just toggling to it).   ;Quote:...devices[1]...Guess I should have explained that better. I'm using a two-monitor environment, and that is the device for my second monitor. Code could be incorrect, but I'm just cobbling together bits and pieces I've found from various sources. I get the same behavior if I use devices[0] too (main monitor).Quote:Anyway, could you post the actual change code? If it's just a ChangeDisplaySettingsEx, then I think you need a AdjustWindowRectEx too.I'm not sure I understand what 'actual change code' you're referring to. That is every line of code I use up through when I get the glError. I do have AdjustWindowRectEx too, its the last line before CreateWindowEx.Quote:What happens if you start with fullscreen initially? (not just toggling to it). I'm not sure how you would do this.Thanks for looking.   ;  Sorry, I guess it's morning.I was referring to your change-to-fullscreen code. When you push the "change-to-fullscreen-key".Or maybe I misunderstood something."This section is the only difference I have between fullscreen and windowed mode, just changing some Display Settings"I don't understand this sentence. Clarifying "some Display Settings" would be useful.   ;  Oh sorry. This is the initialization code for my program, I'm not changing it once its running.Program opens with WinMain, WinMain calls CreateGLWindow, CreateGLWindow calls CreateWindowEx which causes WM_SIZE message where the opengl error is caught.When I said the only difference between fullscreen and windowed mode, I meant that I'm selecting fullscreen or windowed mode by hardcoding variable 'fullscreen' to true or false. When I start defined to windowed mode initialization works fine, if I start in fullscreen mode the initialization is causing errors. I said I was 'changing Display Settings' because I was calling the winapi function "ChangeDisplaySettings". Not actually changing anything once its running.   ;  What happens if you remove the device-lister stuff, and just use hard-coded devmode settings for the fullscreen?My window create for fullscreen:AdjustWindowRectEx(&WindowRect, WS_POPUP|WS_VISIBLE, FALSE, WS_EX_TOPMOST);CreateWindowEx(WS_EX_TOPMOST,WIND_CLASS_NAME,WIND_CLASS_NAME,WS_POPUP|WS_VISIBLE,...You doesn't seem to use the dwExstyle (you pass NULL instead)   ;  Maybe you miss this from the device lister stuff:memset(&dd,0,sizeof(DISPLAY_DEVICE));memset(&dm,0,sizeof(DEVMODE));//the same for other DEVMODE variablesdm.dmSize = sizeof(DEVMODE);//the same for other DEVMODE variablesThere are some flags that need to be set to zero (or something else). I use zero.   ;  Found the problem, I was calling setup projection on WM_SIZE event. For some reason when using WS_POPUP style on the first WM_SIZE event the OpenGL context is not ready, although when using the WS_OVERLAPPEDWINDOW style the context is ready on the first WM_SIZE event.Anyway just threw an if(isInitialized) check around my projection setup and its got no problem now.   