Reload Raylib GUI Font After CloseWindow to Restore Button Labels

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Summary

The UI stops rendering button labels after the first screen because CloseWindow() destroys the Raylib context while the global GUI resources (fonts, textures) remain allocated. When the second window is created without re‑initializing those resources, the text drawing calls fail silently, leaving blank buttons.

Root Cause

  • CloseWindow() tears down the internal graphics context.
  • Raygui keeps a static font reference that is created on the first InitWindow() call.
  • After the first window is closed, that reference points to freed GPU memory.
  • Subsequent calls to GuiButton() succeed, but the text rendering path reads invalid font data, so nothing is drawn.

Why This Happens in Real Systems

  • Many graphics libraries cache assets (fonts, shaders) in global/static storage for performance.
  • Closing a rendering surface without resetting the cache leaves dangling pointers.
  • The bug is hidden in simple demos because the first draw works; later draws appear “invisible”.

Real-World Impact

  • Users see functional but label‑less UI, leading to confusion.
  • Debugging time spikes: UI appears to work, but interaction feedback is missing.
  • In production, this can become a regression when screens are dynamically opened/closed (menus, dialogs).

Example or Code (if necessary and relevant)

// Re‑initialize Raygui after each window recreation
void ReinitializeGui()
{
    // Force Raygui to reload its internal default font
    GuiLoadStyleDefault();
}
uint8_t ModeChoice()
{
    InitWindow(460, 90, "Noise type choice");
    // Ensure GUI resources are fresh
    ReinitializeGui();

    bool bRGB = false, bGS = false;
    while (!WindowShouldClose() && !bRGB && !bGS)
    {
        BeginDrawing();
        ClearBackground(WHITE);
        if (GuiButton({20, 20, 200, 50}, "All colors")) bRGB = true;
        if (GuiButton({240, 20, 200, 50}, "Gray Scale")) bGS = true;
        EndDrawing();
    }
    CloseWindow();   // safely destroys the context
    return bRGB ? RGB : GS;
}

How Senior Engineers Fix It

  • Always re‑load or reset GUI assets after a window is recreated (e.g., call GuiLoadStyleDefault() or explicitly reload the font).
  • Encapsulate window lifecycle in a helper that handles both InitWindow and GUI re‑initialization.
  • Prefer a single window design where possible; switch screens internally rather than destroying the window.
  • Add assertions or checks after CloseWindow() to confirm that no GUI calls are made before re‑initialization.

Why Juniors Miss It

  • They assume that closing a window releases all resources automatically.
  • Lack of experience with static/global resource lifetimes in graphics libraries.
  • Tendency to test only the first screen, missing the second‑screen symptom.
  • Often focus on compiler errors rather than runtime visual artifacts, so the blank labels go unnoticed until a user reports them.

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