Question: I am new to graphical programming and following a simple tutorial on SDL.
Hereby, I am facing a problem which I cant find an answer to:
Whenever I open a Window, it just copies whatever is underneath it, and is not white like in the tutorial. I think this may be due to some hidden render buffer (?).

[![Terminal and window that just copied background](https://i.stack.imgur.com/gOlR0.png)](https://i.stack.imgur.com/gOlR0.png)

I am running the following code:

```
 SDL_Init(SDL_INIT_EVERYTHING);

_window = SDL_CreateWindow("EvolutionEngine", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
                           _screenwidht, _screenheight, SDL_WINDOW_OPENGL);

SDL_Event evnt;
while(SDL_PollEvent(&evnt) == true)
{
    switch (evnt.type)
    {
    case SDL_QUIT:
        _gameState = GameState::EXIT;
        break;
    case SDL_MOUSEMOTION:
        std::cout << "(" << evnt.motion.x << "," << evnt.motion.y << ")\n";
        break;
    }
}

```

(These are in different functions, but the only relevant code to the problem).
My qmake file looks like this:

```
QT       += core
QT       -= gui
TARGET = Evolution
CONFIG   += console
CONFIG   -= app_bundle
TEMPLATE = app
CONFIG += link_pkgconfig
PKGCONFIG += sdl2

QMAKE_CXXFLAGS += -std=c++11
SOURCES += \
...
HEADERS += \
...

```

Has anybody got an idea on what might cause this an how I can fix it?

Answer: 
You are requesting a window with an opengl context form SDL. But you never draw anything to it (including clearing the buffer). I don't know why you would expect a white image from that. The contents of your frame buffer will just be completely *undefined*. And what you get is one of the many possibilities of how such undefined content might look.
To fix your mouse position printing, replace + with <<.