I just re-started again my openGL study lately, since I haven't touched it for a long time I decided to study it all over again and I found an annoying problem....I just can't clear the screen buffer with the color I already selected.....(I use fullscreen mode) here's my code :

#include <windows.h>
#include <gl\gl.h>
#include <gl\glu.h>
#include <gl\glaux.h>

HWND hWnd = NULL;
WNDCLASSEX wnd;
MSG msg;
HDC hdc = NULL;
HGLRC hrc = NULL;

LRESULT CALLBACK wndProc(HWND, UINT, WPARAM, LPARAM);
bool initWindow(HINSTANCE, char *, char *, int, int, int, int);
bool initGL(void);
void killWindow(void);


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,LPSTR lpCmdLine, int nShowCmd)
{	
	
	char szClassName[] = TEXT("RZ");
	
	if( !initWindow(hInstance,szClassName,"OpenGL keren euy!!",800,600,16,nShowCmd))
		return 0;

	
	while(true)
	{
		if(PeekMessage(&msg,NULL,0,0,PM_REMOVE) )
		{
			if(msg.message == WM_QUIT)
			{
				MessageBox(NULL,"hehe","hahaha",MB_ICONERROR);
				::killWindow();
				break;
			}

			
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	
	}

	//MessageBox(NULL,"hehe","hehe",MB_ICONERROR);
		
	return 0;
}


LRESULT CALLBACK wndProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
{
		
	switch(msg)
	{
		
		case WM_KEYDOWN :	
							PostQuitMessage(0);
	

							return 0;


	}

	return DefWindowProc(hwnd,msg,wparam,lparam);
}


bool initWindow(HINSTANCE hInstance, char *szClassName, char *title, int width, int height, int bits, int nShowCmd)
{
	
	DWORD dwstyle;
	DWORD dwExstyle;

	RECT winrect;
	winrect.top = (long)0;
	winrect.bottom = (long)height;
	winrect.left = (long)0;
	winrect.right =(long)width;
	
	
	wnd.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC;
	wnd.lpfnWndProc = wndProc;
	wnd.cbClsExtra = 0;
	wnd.cbWndExtra = 0;
	wnd.hInstance = hInstance;
	wnd.hIcon = LoadIcon(NULL,IDI_APPLICATION);
	wnd.hCursor = LoadCursor(NULL,IDC_ARROW);
	wnd.hbrBackground = NULL; //(HBRUSH) GetStockObject(WHITE_BRUSH);
	wnd.lpszMenuName = NULL;
	wnd.lpszClassName = szClassName;
	wnd.cbSize = sizeof(WNDCLASSEX);
	wnd.hIconSm = NULL;
	

	if( !RegisterClassEx(&wnd) )
	{
		MessageBox(NULL,"hahaha","gagal men!!",MB_ICONERROR);
		return false;
	}

	DEVMODE dm;

	memset(&dm,0,sizeof(dm));

	dm.dmSize = sizeof(dm);
	dm.dmPelsWidth = width;
	dm.dmPelsHeight = height;
	dm.dmBitsPerPel = bits;
	dm.dmFields = DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;
	

	if(ChangeDisplaySettings(&dm,CDS_FULLSCREEN) != DISP_CHANGE_SUCCESSFUL )
	{
		MessageBox(NULL,"hohoho","gagal maning....",MB_ICONERROR);
		return false;
	}

	dwstyle = WS_POPUP;
	dwExstyle = WS_EX_APPWINDOW;

	AdjustWindowRectEx(&winrect,dwstyle,FALSE,dwExstyle);





	hWnd = CreateWindowEx(dwExstyle,szClassName,"openGL keren euy",WS_CLIPSIBLINGS|WS_CLIPCHILDREN|dwstyle,
							0,0,winrect.right-winrect.left,winrect.bottom-winrect.top,NULL,NULL,
							hInstance,NULL);


	if( !hWnd )
	{
		killWindow();
		MessageBox(NULL,"hehehe","gagal lagi men!!!",MB_ICONERROR);
		return false;
	}


	static	PIXELFORMATDESCRIPTOR pfd=
	{
		sizeof(PIXELFORMATDESCRIPTOR),					// Size Of This Pixel Format Descriptor
		1,								// Version Number
		PFD_DRAW_TO_WINDOW |						// Format Must Support Window
		PFD_SUPPORT_OPENGL |						// Format Must Support OpenGL
		PFD_DOUBLEBUFFER,						// Must Support Double Buffering
		PFD_TYPE_RGBA,							// Request An RGBA Format
		bits,								// Select Our Color Depth
		0, 0, 0, 0, 0, 0,						// Color Bits Ignored
		0,								// No Alpha Buffer
		0,								// Shift Bit Ignored
		0,								// No Accumulation Buffer
		0, 0, 0, 0,							// Accumulation Bits Ignored
		16,								// 16Bit Z-Buffer (Depth Buffer)
		0,								// No Stencil Buffer
		0,								// No Auxiliary Buffer
		PFD_MAIN_PLANE,							// Main Drawing Layer
		0,								// Reserved
		0, 0, 0								// Layer Masks Ignored
	};
	
	hdc = GetDC(hWnd);

	if( !hdc )
	{
		killWindow();
		MessageBox(NULL,"huahahaha","gagal lagi nih....huaaaaaaaaa....",MB_ICONERROR);
		return false;
	}

	GLuint pixelformat;

	pixelformat = ChoosePixelFormat(hdc,&pfd);

	if( !pixelformat )
	{
		killWindow();
		MessageBox(NULL,"hihihihi","gagal mulu hiks....",MB_ICONERROR);
		return false;
	}

	if( !SetPixelFormat(hdc,pixelformat,&pfd) )
	{
		killWindow();
		MessageBox(NULL,"hoekhokehoekh....","gagal....",MB_ICONERROR);
		return false;
	}

	hrc = wglCreateContext(hdc);

	if( !hrc )
	{
		killWindow();
		MessageBox(NULL,"huhuhuhuhu....","gagal....",MB_ICONERROR);
		return false;
	}

	if( !wglMakeCurrent(hdc,hrc) )
	{
		killWindow();
		MessageBox(NULL,"yeeeeeee....","gagal....",MB_ICONERROR);
		return false;
	}

	
	ShowWindow(hWnd,SW_SHOW);
	SetFocus(hWnd);

	if (height==0)										// Prevent A Divide By Zero By
	{
		height=1;										// Making Height Equal One
	}

	glViewport(0,0,width,height);						// Reset The Current Viewport

	glMatrixMode(GL_PROJECTION);						// Select The Projection Matrix
	glLoadIdentity();									// Reset The Projection Matrix

	// Calculate The Aspect Ratio Of The Window
	gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

	glMatrixMode(GL_MODELVIEW);							// Select The Modelview Matrix
	glLoadIdentity();										// Reset The Modelview Matrix
	
	initGL();


	return true;
}

bool initGL(void)
{
	//MessageBox(NULL,"tes","testing",MB_ICONERROR);
	
	glShadeModel(GL_SMOOTH);
	glClearColor(1.0f,1.0f,0.0f,0.0f);
	glClearDepth(1.0f);
	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LEQUAL);	
	glHint(GL_PERSPECTIVE_CORRECTION_HINT,GL_NICEST);
	return true;
}

void killWindow(void)
{
	ChangeDisplaySettings(NULL,0);
	
	if( hrc )
	{
		if(!wglMakeCurrent(NULL,NULL))
		{
			MessageBox(NULL,"gagal","gagal ah...cape....",MB_ICONERROR);
		}

		if(!wglDeleteContext(hrc))
		{
			MessageBox(NULL,"gagal","gagal ah...cape deh....",MB_ICONERROR);
		}
		hrc = NULL;
	}

	if( !ReleaseDC(hWnd,hdc))
	{
			MessageBox(NULL,"gagal","gagal...cape deh ah....",MB_ICONERROR);
			hdc = NULL;
	}
	
	
	if( !DestroyWindow(hWnd) )
	{
		MessageBox(NULL,"huahahaha","gagal men...hiks....",MB_ICONERROR);
		hWnd = NULL;
	}

}

I wonder if I miss or forget something? thanks before.

You're using a double buffer, but you don't swap them anywhere.

what a dumn mistake I made.....
thanks for your help.