[rcore] Desktop full screen offset on y-axis

[FedericoMansutti]

Issue description

There is a slight offset on the y -axis after the screen is filled with Init window InitWindow(0, 0, "raylib");
It appears to not be setting the window to undecorated but computing the window size as the full monitor size, so the window origin ends up at a -y.

Environment

Platform: Desktop
OS: Windows 11
GPU: AMD RX 7900 XTX
Reproducible in both the mingw32 compiler (VSCode) and msvc (VStudio)

Issue Screenshot

VStudio (msvc)

VSCode (ming32)

Interestingly this issue seems worse on VStudio.

Code Example

int main()
{
    // Initialization
    //--------------------------------------------------------------------------------------
    InitWindow(0, 0, "raylib");

    int currentMonitor = GetCurrentMonitor();

    camera.position = Vector3{ 10.0f, 10.0f, 8.0f };
    camera.target = Vector3{ 0.0f, 0.0f, 0.0f };
    camera.up = Vector3{ 0.0f, 1.0f, 0.0f };
    camera.fovy = 60.0f;
    camera.projection = CAMERA_PERSPECTIVE;

    //--------------------------------------------------------------------------------------
    int targetFPS = GetMonitorRefreshRate(currentMonitor);
    SetTargetFPS(targetFPS);             // Set our game to run at the monitor refresh rate
    //--------------------------------------------------------------------------------------

    // Main game loop
    while (!WindowShouldClose())    // Detect window close button or ESC key
    {
        UpdateDrawFrame();
    }

    // De-Initialization
    //--------------------------------------------------------------------------------------
    CloseWindow();                  // Close window and OpenGL context
    //--------------------------------------------------------------------------------------

    return 0;
}

Current workarounds:

1. SetConfigFlags(FLAG_FULLSCREEN_MODE);
2. SetConfigFlags(FLAG_WINDOW_RESIZABLE);
   InitWindow(screenWidth, screenHeight, "raylib [core] example - basic window");
   MaximizeWindow();

[ABD-01]

Hi!

I was trying to work on this issue.
I was able to reproduce the same issue on Windows with:

• GCC version 14.2.0
• raylib version 5.6-dev (current master)

Reproducing the Bug

To debug, I added a small green square in the top-left corner of the window.

With InitWindow(800,600,...) the square renders correctly

And

with InitWindow(0, 0, ...), the green dot is not visible — exactly as FedericoMansutti observed — likely due to a negative Y offset introduced during window placement.

After diving into the code, I believe this issue lies with Windows/GLFW rather than raylib. (I'll demonstrate why.)

Code Walkthrough

Here is the flow for code
First of all see Function SetDimensionsFromMonitor

https://github.com/raysan5/raylib/blob/master/src/platforms/rcore_desktop_glfw.c#L1294-L1297

void InitWindow(int width = 0, int height = 0, const char *title)
{
    CORE.Window.screen.width = width;
    CORE.Window.screen.height = height;

    int result = InitPlatform();
    ...
}

// file: raylib/src/platforms/rcore_desktop_glfw.c
int InitPlatform(void)
{
        bool requestWindowedFullscreen = (CORE.Window.screen.height == 0) && (CORE.Window.screen.width == 0);
        int creationWidth = CORE.Window.screen.width != 0 ? CORE.Window.screen.width : 1;
        int creationHeight = CORE.Window.screen.height != 0 ? CORE.Window.screen.height : 1;

        // a window with height and width of 1x1 is created
        platform.handle = glfwCreateWindow(creationWidth, creationHeight, (CORE.Window.title != 0)? CORE.Window.title : " ", NULL, NULL);

            SetDimensionsFromMonitor(monitor); // here is where window size variable is set to display size

            if (requestWindowedFullscreen) // this is set true when height and width are passed 0x0
                glfwSetWindowSize(platform.handle, CORE.Window.screen.width, CORE.Window.screen.height); // set the window size.   
}

// file: src/external/glfw/src/window.c
GLFWAPI void glfwSetWindowSize(GLFWwindow* handle, int width, int height)
{
    ...
    _glfw.platform.setWindowSize(window, width, height); 
    // this is set to _glfwSetWindowSizeWin32 in external/glfw/src/win32_init.c
    // .setWindowSize = _glfwSetWindowSizeWin32,
}

// file: raylib/src/external/glfw/src/win32_window.c
void _glfwSetWindowSizeWin32(_GLFWwindow* window, int width, int height)
{
    if (window->monitor)
    {
        if (window->monitor->window == window)
        {
            acquireMonitorWin32(window);
            fitToMonitor(window);
        }
    }
    else
    {
    ...

fitToMonitor is defined here in src/external/glfw/src/win32_window.c

Verifying if the bug is in Raylib or with Windows

Now, to test this I wrote a similar program without using raylib, but following the same flow of code.
The code is too long so attaching the link

here: test_fitToMonitor.c

The top left drawing was supposed to be a square, however some part of it gets hidden -ve y offset

But with 800x600 window, you get perfectly nice square