SDL2 doesn't render a window

Question

A tutorial's code from LazyFoo wonderful place's 01_hello_SDL page doesn't show a white form, but a desktop's screen, like a screenshot. Something like:

The code:

//Using SDL and standard IO
#include <SDL2/SDL.h>
#include <stdio.h>

//Screen dimension constants
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;

int main( int argc, char* args[] )
{
    //The window we'll be rendering to
    SDL_Window* window = NULL;

    //The surface contained by the window
    SDL_Surface* screenSurface = NULL;

    //Initialize SDL
    if( SDL_Init( SDL_INIT_VIDEO ) < 0 )
    {
        printf( "SDL could not initialize! SDL_Error: %s\n", SDL_GetError() );
    }
    else
    {
        //Create window
        window = SDL_CreateWindow( "SDL Tutorial", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN );
        if( window == NULL )
        {
            printf( "Window could not be created! SDL_Error: %s\n", SDL_GetError() );
        }
        else
        {
            //Get window surface
            screenSurface = SDL_GetWindowSurface( window );

            //Fill the surface white
            SDL_FillRect( screenSurface, NULL, SDL_MapRGB( screenSurface->format, 0xFF, 0xFF, 0xFF ) );

            //Update the surface
            SDL_UpdateWindowSurface( window );

            //Wait two seconds
            SDL_Delay( 2000 );
        }
    }

    //Destroy window
    SDL_DestroyWindow( window );

    //Quit SDL subsystems
    SDL_Quit();

    return 0;
}

Putting PumpEvents(); or while(SDL_PollEvent(&event))... didn't work, unfortunately.

The machine's characteristics:

• CPU: i7 M620
• GPU: Intel Core Processor Integrated Graphics Controller
• GPU Driver: i915
• RAM: 8GB
• OS: KDE Neon 5.15.4 64bit, 4.15.0-47 Kernel, fully updated

Answer 1

By experimenting, we found that adding a short delay(~100ms) at the very start(after SDL_CreateWindow) fixes the issue. This might mean that there was a conflict between the OS's Dekstop/Window Manager and SDL when the latter renders too quickly. A short delay forces SDL to wait some time while OS's Dekstop/Window Manager handles the window's creation. This might also be something related to the compositor, which in our case - compiz.

In other words, the changes:

...
// Create window
window = SDL_CreateWindow("SDL Tutorial", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
SDL_Delay(100); // A short delay should be put here(if doesn't work try increasing delay)

if(window == NULL)
{
...

With these changes, the white window opens successfully.

'Already wrote to the author of LazyFoo and hopefully they will alter the tutorial.