Opengl texturing (with mimap or not) from a FBO - opengl

Question

I must be missing something obvious in using FBO :
I call TMyForm::Init() once at the start of my application :
class TMyForm
{ ...
private:
Gluint mTextureId, mFboId;
int mWidth, mHeight;
}
void TMyForm::Init()
{
mWidth = 1920;
mHeight = 1080;
...
// create a texture object
glEnable(GL_TEXTURE_2D);
glClearColor ( 0.0, 0.0, 0.0, 1.0 );
glGenTextures(1, &mTextureId);
glBindTexture(GL_TEXTURE_2D, mTextureId);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE); // automatic mipmap
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 1920, 1080, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
glBindTexture(GL_TEXTURE_2D, 0);
// create a framebuffer object
glGenFramebuffersEXT(1, &mFboId);
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, mFboId);
// attach the texture to FBO color attachment point
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, mTextureId, 0);
// switch back to window-system-provided framebuffer
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
}
And in the Draw() function I send the buffer to a card (the rendered scene is ok) and to a preview window (all black or all white depending if I switch back to default window context or the fbo context) :
void TMyForm::Draw()
{
// set rendering destination to FBO
glEnable(GL_TEXTURE_2D);
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, mFboId);
//---
glViewport(-1920, -1080, 1920 * 2, 1080 * 2);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(double(-iWidth)*viewport_ratio, double(iWidth)*viewport_ratio, double(-iHeight), double(iHeight), 1000.0, 100000.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
Render();
glFlush();
//--- 1 : send to card
delete[] mBufferPlayout;
mBufferPlayout = NULL;
try
{
mBufferPlayout = new GLubyte [mWidth * mHeight * 4];
glReadBuffer(GL_COLOR_ATTACHMENT0_EXT);
glReadPixels(0,0, mWidth, mHeight, GL_BGRA_EXT, GL_UNSIGNED_BYTE, mBufferPlayout);
DisplayFrame(mBufferPlayout);
}
catch (TSCDbException &e) { ShowMessage(GetLastError()); }
//--- 2 : Texturing to the preview window :
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
glClear(GL_COLOR_BUFFER_BIT);
glBindTexture(GL_TEXTURE_2D, mTextureId);
//glGenerateMipmapEXT(GL_TEXTURE_2D);
int iWidthPreview = mWidth / 2; // ie 960
int iHeightPreview = mHeight / 2; // ie 540
glViewport(-iWidthPreview, -iHeightPreview, iWidthPreview * 2, iHeightPreview * 2);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(double(-iWidthPreview), double(iWidthPreview), double(-iHeightPreview), double(iHeightPreview), 1000.0, 100000.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.0, 0.0, -50000.0);
mxIncrust0 = 0.0; myIncrust0 = 0.0;
mxIncrust1 = iWidthPreview; myIncrust1 = iHeightPreview;
glBegin(GL_QUADS);
glColor4ub(255,255,255,255);
glTexCoord2d(0.0, 0.0); glVertex2d(mxIncrust0, myIncrust0);
glTexCoord2d(0.0, 1.0); glVertex2d(mxIncrust0, myIncrust1);
glTexCoord2d(1.0,1.0); glVertex2d(mxIncrust1, myIncrust1);
glTexCoord2d(1.0,0.0); glVertex2d(mxIncrust1, myIncrust0);
glEnd();
glDisable(GL_TEXTURE_2D);
glFlush();
//---
SwapBuffers(ghDC);
}
So my problem is the "part 2" which does not do what I wish : texturing the fbo content to the current window.
I tried changing the "glTexCoord2d" with no success.