SDL_FlashWindow() platform support

The SDL_FlashWindow() function is supported on most major platforms, but its behavior may vary depending on the underlying operating system. Currently, SDL_FlashWindow() works on Windows, macOS, and some Linux desktop environments that support window manager hints.

On unsupported platforms or window managers, the function is effectively a no-op, meaning it won't cause any harm but also won't produce any noticeable result.

Platform-Specific Details

• Windows: SDL_FlashWindow() triggers the taskbar icon to flash or the window to draw attention, depending on the flash mode you specify.
• macOS: The function typically causes the dock icon to bounce, which is a common way to attract user attention on macOS.
• Linux: Support depends on the window manager. Popular environments like GNOME and KDE are likely to support it, but minimal window managers may not respond to flash requests.

Here's a program to test flash functionality:

1#include <SDL.h>
2#include <iostream>
3
4int main() {
5  if (SDL_Init(SDL_INIT_VIDEO) != 0) {
6    std::cout << "SDL_Init Error: " <<
7      SDL_GetError() << '\n';
8    return 1;
9  }
10
11  SDL_Window* window =
12    SDL_CreateWindow(
13      "Flash Test",
14      SDL_WINDOWPOS_CENTERED,
15      SDL_WINDOWPOS_CENTERED,
16      640, 480,
17      SDL_WINDOW_SHOWN
18    );
19  if (!window) {
20    std::cout << "SDL_CreateWindow Error: "
21      << SDL_GetError() << '\n';
22    SDL_Quit();
23    return 1;
24  }
25
26  std::cout << "Flashing window\n";
27  SDL_FlashWindow(
28    window, SDL_FLASH_UNTIL_FOCUSED);
29
30  SDL_Delay(5000);
31  SDL_DestroyWindow(window);
32  SDL_Quit();
33  return 0;
34}

If you're using an unsupported platform or window manager, you might need to implement custom attention-grabbing techniques.

For example, changing the window's title or using SDL_SetWindowAlwaysOnTop() as a workaround.

Verifying Support

To check if SDL_FlashWindow() is supported on your platform, test the behavior and consult your system documentation. SDL itself doesn't provide a direct function to query flash support, so experimentation is your best bet.